AbstrAct: Enabled by the Internet-Web compound, co-creation of value by consumers has emerged as a major force in the marketplace. In sponsored co-creation, which takes place at the behest of producers, the activities of consumers drive or support the producers' business models. Autonomous co-creation is a wide range of consumer activities that amount to consumer-side production of value. thus, individuals and communities have become a significant, and growing, productive force in e-commerce. to recognize co-creation, so broadly understood, as a fundamental area of e-commerce research, it is necessary to attain an integrated research perspective on this greatly varied, yet cohering, domain. the enabling information technology needs to be developed to suit the context. toward these ends, the paper analyzes the intellectual space underlying co-creation research and proposes an inclusive taxonomy of Web-based co-creation, informed both by the extant multidisciplinary research and by results obtained in the natural laboratory of the Web. the essential directions of co-creation research are outlined, and some promising avenues of future work discussed. the taxonomic framework and the research perspective lay a foundation for the future development of co-creation theory and practice. the certainty of turbulent developments in e-commerce means that the taxonomic framework will require ongoing revision and expansion, as will any future framework. KEy Words And phrAsEs: Active consumption, co-creation, consumer roles, e-commerce research, taxonomic frameworks. The clear separation between the production and consumption domains is a matter of the last three centuries. 1 During the last two decades, there has appeared, and is gathering strength, a phenomenon that points in the opposite direction. Empowered by the Internet-Web compound (hereinafter the Web) and the associated information technologies (IT), consumers have been producing marketable value. This is changing the role of consumers in the marketplace and, more broadly, the role of individuals versus organizations. This also challenges our understanding of work-and of the rewards it brings. The discussion that follows frames an integrated perspective on this phenomenon. Co-creation is here defined broadly as the creation of value by consumers. Sponsored co-creation comprises co-creation activities conducted by consumer communities or by individuals at the behest of an organization (termed the producer). In autonomous co-creation, individuals or consumer communities produce marketable value in voluntary activities conducted independently of any established organization, although they may be using platforms provided by such organizations, which benefit economically. Marketable value is not necessarily consigned to the market-it may be placed in the commons, as is the case with Wikipedia. Sponsored co-creation is exemplified by Procter & Gamble and IBM, which seek product ideas from unaffiliated individuals in well-organized contests and jams. Combining autonomous and sponsored 01 zwass.indd 11 10/6/2010 1:33:30 PM co-creation, and on a different scale, the Polyvore e-commerce site enables consumer visitors to assemble on-screen images of garments and shoes from various e-stores into the consumers' style statements; it also runs idea contests. IT enables both endeavors: Some IBM jams are run on the Second Life platform, while others use interlinked bulletin board and Web pages. Polyvore uses an innovative technology for aggregating images from the Web. It benefits from co-creation in several ways: Consumers' preferences are ranked and analyzed, yielding vital real-time information; consumers' creative ideas can be marketed to producers; producer contests are run to test new ideas (and, with interest amplified by these opportunities, the site receives sellers' commissions and consumers are exposed to ads). Such iconic products of autonomous co-creation as open source software (OSS) and Wikipedia have changed the competitive landscape of the software and knowledge industries-and continue to do so. Consumer reviews provided by individuals form a large part of the value of many Web sites-and are furnished in autonomous co-creation. Thus, consumers are no longer just passive value takers, but have emerged as value makers in both individual and collective actions. Co-creation is here treated broadly as the activities of individuals/consumers/users in the production domain, generated independently or at the behest of producer organizations. As will be argued, such a broad research program enables the development of theories and analytical approaches that cut through divisions that are rapidly becoming artificial. Indeed, the methods of process governance in the domain, and so too the motivating factors, have much in common whether one analyzes sponsored or autonomous co-creation. The integrated approach will serve well as business methods evolved in co-creation are adapted and adopted for intra-organizational use. A major objective of this paper is to stimulate research on this broad subject within the transdisciplinary field of e-commerce, which is uniquely suited to this purpose. Seeing the phenomenon whole will further enable seeking competitive advantage in the marketplace with the contributions of co-creating consumers, developing Web-based technology to enable co-creation, enacting the motivators by communities and firms, and thus empowering individuals to lead a fuller life. The need for close study can be clearly seen from the dominant tropes. When one speaks in a context-free manner about "crowdsourcing" or the "wisdom of crowds," one glosses over a number of issues, such as how to select contributors from the crowd, how to organize the sourcing to make sure of a satisfactory outcome, what incentives to provide to that part of the "crowd" that can truly contribute, how to assess the process and the product, and indeed, whether the "crowd" is smart enough for what we are trying to do. An ultimately comprehensive taxonomic framework is needed that would contextualize research efforts in the area of co-creation. By developing models in specific contexts and studying the impacts of specific factors on the outcomes, using the theories and instrumentalities of various disciplines, a cumulative body of knowledge will be created in the field. A broad perspective for such a framework is needed for knowledge cumulation. In the present discussion, the top-ranked journals in the relevant disciplines of information systems, marketing, electronic commerce, computer science, 01 zwass.indd 12 10/6/2010 1:33:30 PM economics, and related fields have been consulted. Other works are cited as appropriate, with only the references essential to the argument stated, in the interest of relative concision and readability. Illustrations have been drawn from e-commerce practice, a laboratory in turbulent action. The presentation is aimed at diverse audiences. This is a vast terrain, and capturing its scope is bound to come at the expense of detail, if the treatment is to be bounded by the customary length of the genre. After this introduction, the paper is structured as follows. The nature of co-creation and the reason it has emerged as a significant force in the 1990s is discussed next. The intellectual space forming around the nodal aspects of the phenomenon is explored next. This space includes the study of: virtual communities, where much of the value contribution occurs; the commons, where such co-created artifacts as OSS are freely revealed for open access; collective intelligence, the emergence of intelligent behavior to surpass the intelligence of the individual members of certain collectives; and open innovation, the producer firms opening themselves to co-creation in new product development. The two following sections classify the two essential supra-components of the taxonomic framework proposed here. The first of these sections describes the typology of value co-created autonomously and in symbiosis with producer organizations. The second one classifies the salient aspects of co-creation into a taxonomic framework. The most prominent research directions are discussed next, offering a perspective on this research domain. The conclusions follow. Co-creation is the participation of consumers along with producers in the creation of value in the marketplace. Activities of this kind go well beyond the notion of co-creation as conceived in services that are, to an extent, jointly actualized by their suppliers and the receiving customers. They also go beyond mass customization, as it aims to satisfy cost-effectively the needs and wants of a specific individual. Co-creation may be initiated by producer firms or by consumers themselves. Indeed, in this definition, participants in many co-creation activities are considered consumers only in contrast to producers. Co-creation was originally defined in the late 1990s by Kambil and his co-authors as co-creation of value by a firm's customers [54, 55] . 3 This meaning has been gradually extended toward autonomous individual initiatives [24] . With the technologically enabled broad movement of individuals into productive activities, it is worthwhile to study the strategies, methods, and technologies of co-creation in an integrated manner. 4 Thus, OSS development methods, elaborated by communities of volunteer developers, are being ported into organizations, along with the products of these communities. 5 Ludic, or play, communities, provided only with a platform, develop a virtual life that builds monetary value for the platform-maintaining firms. Blog aggregators evolve new forms of on-line newspapers. Communities of practice evolve and freely reveal substantive knowledge stocks, untethered to specific producers. New forms of production are thus emerging and evolving in the voluntary sphere 01 zwass.indd 13 10/6/2010 1:33:30 PM that are increasingly permeating the productive sphere, knowledge creation, capital formation, and the very fabric of work. Wikipedia and SourceForgecentered OSS projects are laboratories of evolving organizational approaches to channeling the knowledge and efforts of individuals into products. Integrated study of the domain will further our understanding of this evolution enabled by IT and will underwrite the seamless use of best approaches across the B2C and C2C sectors. The nature of the goods that dominate co-creation is of the essence. These goods are digital and nonrival (not consumed in use and thus available to all who have access); they are also not easily excludable, as some are intentionally available to all having access even without a reciprocal contribution, while others generally can be "liberated" (pirated) through a contravention of security measures, and against legal and ethical constraints. Network effects present in the case of some of these goods make them more valuable to each user as the number of users increases-the more contributors there are on a review site, the more visitors and the likelier future contributions. Two-sided network effects are also present in some cases-the more individuals use an OSS product, the more valuable is the experience its creators garner, and the more likely is the product to be well maintained for future use by motivated developers. Beyond this, the collective processes of sharing data, information, and knowledge in the digital domain by individuals vastly contribute to the growth of co-creation activities. Many of the underlying motives that drive individuals to co-creation, such as volunteering and other types of social action on the one hand, and repurposing of products for one's own use on the other, are not the epiphenomena of the Web. Yet, co-creation has emerged owing to the ubiquity and accessibility of the Web in its multiple aspects. The qualitatively different scale of the phenomenon derives from the fact that the Web presents, simultaneously and synergistically, several major aspects bearing the relevant opportunities: marketplace, universal supply-chain linkage, network of relationships, collaboratory, forum, interactive medium, and distribution channel [117] . In the specific relation to co-creation, we now have the following enablers and drivers: 1. Broadly accessible means of production are available, that in many ways are indistinguishable from the means of consumption. The Web-Internet stack and the means of access are ubiquitous in the developed and in much of the developing world, and both general and computer literacy is spreading as well, including at this time more than a billion people. Moving toward universality, IT artifacts and the infrastructure on which they are deployed become even more accessible with the smartphone as the evolving primary access device. Producing opinions, encyclopedia articles, or software faces only the barriers of knowledge. Roles are becoming fluid as well. Zazzle offers on demand a multitude of customized retail products, but the point is that a Zazzle consumer can very easily become a producer and marketer of the good he or she has just co-created. A reader of a Wikipedia article can almost instantaneously become the co-author (or even the new author) of the article, if not necessarily with a salubrious outcome. The users 01 zwass.indd 14 10/6/2010 1:33:30 PM of an OSS product can become co-creators with its developers [62] . This is "the wiki way"-consumption and production can be intertwined. Recursively, OSS products are freely available to users who know how to use them and who can co-create new OSS using them. 2. The Web provides the means of coordination of effort. The Web's ubiquity and the IT tools available for access serve to harmonize the efforts of individuals in a common action, the very definition of coordination. For example, the tools for organizing OSS projects are available on SourceForge. Wikipedia has accreted a powerful set of means of organizing the widely distributed production of articles. Idea contests or information markets provide a different form of coordination of contributors. As we move broadly to m-commerce, this is even more so. 3. The Web furnishes a broadly dispersed means of aggregation of digital products. Version-control systems for OSS enable tight control of the builds on a daily basis. The existing Wikipedia structure provides an evolving means of organizing the contributions and their history, in multiple languages, and embedded in many cultures. Hyperlinking to create new content and blog aggregation are other cases in point. Real-time search of Twitter feeds is a newer, and powerful, method of gauging sentiment by aggregation. 4. With the widely spread and economically accessible Internet and Web IT, there is now a global digital means of distribution for digital products, encompassing sourcing and mass access. As the use of the platform stack spreads ever more widely, in particular into the mobile domain, and as new firms providing innovative business platforms based on it emerge, and the competition among established and emerging firms intensifies, one may expect tempestuous developments in the distribution of the products of co-creation. As an important example, Benkler characterizes "computation and storage" as "lumpy" goods, available only in discontinuous amounts of functionality and capacity [11, p. 113]. With the rapid advance of cloud computing, the discontinuities disappear, and access to hardware and software resources, and thus to ever more sophisticated means of production and distribution, is further facilitated. The broad availability of the means of production, effort coordination, product aggregation, and distribution acting synergistically has a powerful effect on the continuing development of co-creation. Co-creation is underwritten by several developments that have accreted research literatures and traditions. The prominent contributing streams of  Virtual communities (VC) are the primary locus of collective contribution to co-creation. Definitions of VC differ in terms of the intensity of commitment required by the human collective that is regarded as a community. Rheingold, who introduced the concept, defined VC as "social aggregations that emerge from the Net when enough people carry on . . . public discussions long enough, with sufficient human feeling, to form webs of personal relationships in cyberspace" [90, p. 5]. The salient characteristics of the VC are, according to Lee, Vogel, and Limayem, member interactions on-line, production of content by members, and building of relationships among members [64] . Blanchard and Markus go further, expecting feelings of belonging and mutual attachment from community members [13] . Turkle also sees VCs as providers of identity to their members [104] . Indeed, the originator of sociological thinking about communities, Tönnies, who described community (Gemeinschaft) as a counterpoint to society that serves as an association created to further individual self-interest (Gesellschaft), considered a common identity and a degree of surrender to the common good to be the defining characteristics of a community [102] . There are many types of VC, depending on the categorizations. They range from strongly bound communities of affliction to loosely affiliated transac- . E-commerce is directly supported by brand communities: on-line communities based on social relationships among brand adherents [76] . These are important in co-creation in many ways: by the elaboration of user knowledge about the brand's products, by surfacing lead users, and by creating a commitment to the brand that can lead to an intent to contribute to the development of its products. Brand communities may be hosted by the brand or by consumers, with notable differences leading to diversity, freedom of expression, and stronger bonds and member motivations in the latter [30] . Virtual communities can be highly productive generators of social capital. Social capital has been defined as "resources embedded in a social structure that are accessed and/or mobilized in purposive action" [69, p. 29]. Social capital, according to Putnam, "refers to connections among individualssocial networks and the norms of reciprocity and trustworthiness that arise from them" [87, p. 19]. This relatively recently recognized form of capital has been conceptualized to have both a private dimension, with the benefits that accrue to individuals engaging in social relations, and a public dimension, with the benefits accruing to the community within which the ties are enhanced. The society at large benefits from the enhanced levels of trust and cooperation among individuals beyond their own kin [39, 88] . With the emergence of the Web, and the variety of individual relationships whose traces can be digitally captured, analyzed, and aggregated, into this dichotomy between the private and the public steps the third agency-the producer/aggregator able to appropriate some of this capital. Notable in the above quotation from Putnam is that the reference to social networks of the pre-Web type is apt as a reference to social networks on the Web and the capital they give rise to. The structural and relational dimensions of social capital are the most prominent of the three aspects identified by Nahapiet and Ghoshal, while the cognitive dimension is clearly in the background [77] . The outcomes range from the free revelation of knowledge in communities of practice to the less laborious, less obvious, more ubiquitous, and more  The commons are universally shared resources, owned in common, as it were. Wikipedia is an example of a co-produced resource placed for open access in the commons; Creative Commons contains a variety of works contributed by their authors. Open access is a broad movement and worldview, as well as a set of practices. As a nonrival good, digital content can be consumed by anyone without impairing the ability of others to consume it. Property rights, such as intellectual property protections, provide enclosures from the commons. Benkler considers social production with a commons-based open access to be a new production mode that complements and rivals the market and the hierarchy of organizations [11] . However, the economic aspects of the arrangements are likely to assert themselves before co-creation can truly rival the two established production regimes: Co-creators do not conduct their lives in the commons, which places a limit on the extent of co-creation as the need for economic incentives becomes imperative. This having been said, the growth and diversity of this production mode are apparent. Technologically enabled open access to digital content has been most strongly expressed by OSS, which has freely available source code, produced in the most general form by a distributed (globally, with round-the clock advantages) development community. Highly parallel development processes rely on prompt and frequent peer review, and frequent and methodical new releases. Well-understood requirements favor horizontal projects, as opposed to business-oriented systems that would call for extensive systems analysis [34] . Some of the iconic products are Linux, Mozilla, Apache, OpenOffice, and MySQL. As infrastructural systems, many of these further the development of the software industry as a whole [100] . The rights of the commons are asserted for OSS through a variety of more or less restrictive licenses aiming to assure perpetuity in the commons for the original software and its derivatives. Interpreted as an innovation, OSS production can be studied as unremunerated work toward the production of a public good [109] . The practices realign power and market relationships around digital content in the domains of knowledge, information, entertainment, and software products [57] . Research shows that free revealing offers significant private benefits to the co-creator, which are discussed below as motivators of co-creation. Another category of OSS co-creators consists of the users, who are strongly involved in the process, and sometimes carry out most of the system testing and initiate new features [34] . Thus, OSS can be appropriated by users in an active mode, with major benefits to their learning [62] . Recursively, OSS products leverage further OSS projects: Configuration management for OSS projects is performed with a version-control system, such as Concurrent Versioning System (CVS), an OSS itself, or with a newer, distributed, system, such as Bazaar or Git. The nodal role in the OSS movement is played by the SourceForge source-code repository, the Web site supporting 01 zwass.indd 18 10/6/2010 1:33:31 PM OSS developers with coordination and communitarian tools. As of the February 2009 update, the SourceForge repository hosted more than 230,000 projects and more than 2 million registered users. However, as pointed out by Fitzgerald, only a small percentage of the projects listed are stable and mature [35] . Cultural norms regulate the development projects: for example, forking (splitting into rival development projects) is not tolerated, and credit is conscientiously assigned, thereby acting as a motivator. The culture of the commons and, in particular, the culture of open access to and co-creation of derivative cultural works in the digital domain, of remix and mashup, has vocal academic advocates, such as Lessig [67, 68] . It also has respected opponents, such as Lanier, who asserts the primacy of the auteur, and argues that a "hive" cannot create transcendent artifacts or art [63] . Issues pertaining to the definition and protection of intellectual property, and the generation and distribution of revenue emerge from the positions advocated in this realm. Much of co-creation relies on the contributions of collectives, such as VCs, or on asynchronous contributions by individuals, aggregated by one of the methods discussed below. The hypothesized superiority of collective intelligence in various cognitive tasks is therefore a subject of active research interest. The emergence of intelligent behavior in a collective has been described by Surowiecki [99] as the "wisdom of crowds," generating the concept of crowdsourcing [50] . Intellectual predecessors come from various disciplines. Thus, Hayek showed how price serves as an aggregator of the knowledge of many distributed individuals, allowing them to act in a self-organizing system of voluntary cooperation (far more effectively than a central-planning mechanism ever could) [45] . Holland has defined the fundamentals of the complex adaptive systems in which independent agents compete and cooperate, with complex collective behavior emerging in the process [49] . The work continues in several disciplines, creating the science of complexity. Pertinent to co-creation is the emergent coordination of voluntary endeavors without a direct managerial structure or role assignment. One example is the "follow the taillight" project coordination in OSS projects, where the focus on a shared target, such as besting an existing software product, frequently with an emotional engagement, aligns the efforts of a group [12] . The cooperation of group members in working toward their common goal emerges as a behavior learned after repeated, ultimately successful, interactions. This is sometimes characterized as swarming behavior, with analogies to the animal behavioral patterns studied by ethologists. Gloor analyzed a type of VC that he calls a collaborative innovation network, using insights gleaned from this approach [42] . In the co-creation research domain, collective intelligence is studied intensively with respect to information markets (or virtual stock markets) in the applications to forecasting, decision making, and idea generation. Participants in such markets trade contracts whose payoff may depend on a future event.  These markets are considered efficient economically, and often also in the sense of speed, in aggregating the dispersed information and knowledge of diverse individuals. Based on research results that can be traced to the theory of complex adaptive systems, the necessary characteristics of information markets have been determined [49] . These are: the presence of motivators necessary to elicit participation and knowledge revelation; participants with relevant knowledge; diversity of the participants in aspects relevant to the decision; independent decision-making by participants (thus avoiding mutual influence and groupthink); and the presence of an aggregating mechanism (generally the market price, but other possibilities exist, such as popularity points). Information markets are used as prediction, preference, or idea-generation markets. Prediction markets serve to aggregate opinions about the likelihood of future events. This may involve a choice between several discrete alternatives or an estimate of a value (such as sales volume). Preference markets identify the participants' preferences-for a product, for example. Idea-generation markets are deployed to generate new ideas, possibly also identifying the way the future outcome can be estimated and thus a payoff determined. While prediction markets pay off on the underlying event and can use the outcome as the criterion of goodness, the others cannot rely on a fait accompli, as the outcome becomes known only in the longer term. Information markets have been studied in a variety of disciplines, notably and obviously in economics (e.g., [114] ), and have extensive analytical literature. Geng, Stinchcombe, and Whinston presented and formally analyzed a framework for a two-stage Vickrey (sealed-bid-second-price) auction for the introduction of radically new products [41] . The co-creating participants used on-line simulators to exercise the prototypes. Spann and Skiera presented alternative designs of prediction markets and analyzed their forecast accuracy [95] . Effectiveness of a market for idea generation was investigated in an experiment by LaComb, Barnett, and Pan [61]. Ideas were "securitized" and traded on the market, with the idea adjudged the best surfacing as the highest-priced security. The market was found to result in more ideas and attract more participants than more traditional idea-generation techniques, but was no more effective in ranking ideas than others. The nature of the needed reward in information markets has been researched. Real-vs.-play money as payoff was the subject of research by Servan-Schreiber et al. [93] . Play money has been found effective indeed. Chen et al. used play money to investigate voluntary employee participation in an internal preference market and found it effective [18] . Dell and Starbucks experimented with such markets involving customer communities. Jones, Collins, and Berndt present a comprehensive set of research propositions in the information-market landscape [53] . In sponsored co-creation, organizations open themselves to the co-creation efforts of external individuals, including present or potential consumers.  From the point of view of the producer organization, the closed model of innovation, relying principally on internal knowledge stocks and flows to create novel products and processes, is being augmented and modified in this model, known as open innovation, which also includes cooperation with other producers. The general premise is that there are far more potential value creators outside the company than within its walls (or on its internal networks). "Open [i]nnovation is the use of purposive inflows and outflows of knowledge to accelerate internal innovation, and expand the markets for external use of innovation, respectively" [19, p. 1]. In relation to consumers, open innovation aims to attain a rich understanding of their objectives and the way they use the firm's products, and to garner the creative ideas they have about their needs (rather than only with regard to currently used products). Binding consumers to the brand is a clear objective as well. In opening themselves to consumer co-creators, firms are democratizing innovation, in the words of von Hippel [106] . The division of labor between producers and consumers is being redefined. Consumers, as the users of products, know different things than the producers. Consumers can contribute in a variety of roles; some of these are parsed by Nambisan and Nambisan [78] . Their possible contributions are discussed further below. In supporting consumers' co-creation activities, producers can provide toolkits over the Web, assisting consumers/users in designing, prototyping, and testing the products [106] . While some of this activity falls under the rubric of customization for the use of a given individual, certain producers incorporate the ideas and designs proposed by consumers into corporate open innovation processes or expressly support co-creation activities with extensive corporate programs. Innovation intermediaries, such as InnoCentive, have emerged to assist companies in opening their innovation processes to the "world," literally and figuratively. The Web site of InnoCentive seeks solutions proffered by individuals (and firms) globally to well-defined problems of its corporate clients and offers professional services in the processes of vetting and assisting contributors. The open platform code of sites such as Facebook or the support for iPhone apps brings into the compass of the owner firms creative talents and fresh ideas of a highly diverse population of developers, many of them co-creating consumers. The ability to engage customers in the exploration and exploitation of innovation opportunities is seen as a factor of corporate agility in the marketplace [92] . As defined above, co-creation includes autonomous activities by individuals and communities, that is, by consumers as opposed to market-oriented producers, as well as sponsored co-creation in conjunction with a producer. Here we shall consider both. It should be noted that various autonomously co-created products are deployed by organizations characterized as producers, including platform providers (e.g., Amazon, Facebook, TripAdvisor), often acting as information aggregators.  VladImIr ZwaSS The following components of autonomous co-creation can be recognized. The successful autonomous production of OSS has surfaced the ideology, production systems, tools support, wealth of motivations, and means of legally protecting commons property that have become a defining syndrome of co-creation. While the foundations of OSS production have been established, the metasystem that would incorporate this mode of production into the overall IT environment keeps evolving, with major corporations using OSS platforms, reusing OSS code in their own, wrapping OSS products in their for-profit services and support as complementary products, and attempting to deploy the development methods discovered by OSS communities in the corporate development milieu. The great variety of user-created digital content includes the following: • Knowledge compendia. The icon is the Wikipedia model of the continuing accretion and refinement of knowledge content by globally distributed individuals. The spectacular success of the model of open contribution to a commons product can be contrasted with the spectacular failure of the original attempt to offer the Wikipedia based on the traditional model of the accreditation of contributors and editorial supervision. • Consumer reviews. A different model of information aggregation is that of the successful Zagat guides and derivatives, which use material within a limited domain supplied by qualified consumers and aggregate the information by systematization, indexing, summarization, and statistical means. 7 Angie's List, Yelp, and similar sites use variants of this model. Consumer reviews of many kinds are available on technology, travel, cultural products, and so forth, with the best-known aggregates having acquired strong market power. • multimedia content. YouTube is a starring example of the value created by "the world" of contributors. • Blogs. Sometimes highly personal, very timely, and informed by deep knowledge and analysis, on-line journals volunteer coverage of many domains, from the highly specialized to the truly global. Of course, most blogs are of strictly private interest. Blog aggregators like the Huffington Post have created novel news and opinion formats rivaling traditional newspapers. The facilities provided by the aggregator of this content include the platform, the means of classification and search, often with a summary aggregation, and-01 zwass.indd 22 10/6/2010 1:33:31 PM not least-the means of monetization (e.g., advertising, sponsorship) that assure continuing existence. • mashups. These sometimes controversial compositions of existing content can be created and modified by ever new contributors. In the commons, the use of Google Maps combined with local or statistical information often results in high-value products. • Virtual worlds. The contents of a metaverse such as Second Life are created by the users, most of them individuals (although organizational use is growing). Business models of this kind exhibit strong network effects-the benefits to existing users grow supralinearly as new users (and their avatars) join the world. With the drastically falling costs of user-side fabs and the availability of toolkits, consumer-side production of hardware artifacts has been on the increase [3] . Digital prototyping tools and inexpensive stereolitographic 3D printers make it possible to reallocate some production tasks, along with customization, to the consumer side. It may be expected that this trend will go beyond production for one's own use and evolve into value co-creation entailing innovation and the production of marketworthy artifacts. Arduino, the open source prototyping platform for electronics design, is a notable example of an enabler. The increasing volume of digitizable content, such as configuration for field-programmable gate arrays (FPGA) for digital design, supports this trend. The social capital accumulated in Web-based relationships is being used in the creation of value. The relationships among the members of social networks, such as Facebook, the leader, but also MySpace, LinkedIn, Baidu Space, Orkut, QQ Alumni, and others, as expressed by "friending" and other links, and as supplemented by vast disclosures of information, are available for commercial exploitation by the platform owners, subject to legal constraints and ethical norms. Location-based social media in the m-commerce domain, such as Foursquare, enable the accumulation of information on the pattern of the members' movements as customers in the physical world, with the consequent economic leveraging. Trust deficit constitutes a recognized barrier to e-commerce. Indications of counterparties' trustworthiness, or lack thereof, supplied by consumers to transactional platforms, therefore, represent a significant value. Reputation systems aggregate the data for this type of trust. "Reputation is the opinion of the public toward a person, a group of people, an organization, or a resource"  Word of mouth is defined as "all informal communications directed at other consumers about ownership, usage, or characteristics of particular good and services and their sellers" [113, p. 261]. Word-of-mouth (WOM) promotion is vastly amplified on the Web by the availability of massively shared transactional platforms like Amazon, social networks, and other social media, such as the microblogging service Twitter. Linking to, blogging, sending tweets, informing "friends" through collective messages, are among the available ways to engage, in effect, in social product promotion (or demotion). Electronic WOM (eWOM) is subject to social amplification [116] . Reputation systems that evaluate participants coexist with word-of-mouth product reputation articulations [26] . Although they may rely on similar mechanisms in certain aspects, the differences are significant; among other factors, time horizons and reliability criteria differ between the two categories. Platforms offer additional means of aggregating WOM by combining it with reputation systems for opinion-makers, such as Slashdot's karma points. Annotation by consumers and the bottom-up taxonomy emerging from the labeling of items, such as photos on Flickr ("folksonomy"), provide an organizing means and equip the search capability for the context, thus enhancing the value of user-generated content. In an economy where attention rather than information is the scarce resource, the means of directing users' attention to items truly important to them are valuable. This is the foundation of Google's PageRank algorithm-which is based, in essence, on the number of links pointing to Web pages, with further weights assigned, recursively, in the same fashion to the pointing pages. The implicit collective ranking emerges from the page-creation activity of the multitudes. It may be noted that the value absorbed by the owner of the bynow heavily modified algorithm, whose variant is also used and monetized in AdWords, is the positive externality of the regular activity of Web users. Digg's advancement of comments to the home page is another example of such ranking.  The availability of sometimes deep knowledge on certain authoritative Web sites has enabled motivated consumers to share the task of advice or diagnosis with the professionals they retain. This is notable in the "Web-informed patient" syndrome, with patients researching their conditions on WebMD and similar sites, but also using community sites such as PatientsLikeMe that offer deep and hard-earned experiential knowledge. The legal and investment domains, among others, have experienced significant efforts by consumers informing themselves. Professionals in these domains need to equip themselves to be able to take advantage of this co-creation. In sponsored co-creation, consumers can contribute to virtually every stage of the value chain of the organizations that involve them in their activities. The following contribution domains can be recognized, starting with upstream value-chain stages. As the users of products in the most diverse circumstances and the collective possessors of diverse stocks of knowledge and experience, consumers as a whole, and consumer communities as collective bodies, can generate new product ideas, elaborate on ideas generated within organizations, and help to assess the viability of proposed new products. Among the notable and well-known examples, Procter & Gamble (P&G) deploys its Connect + Develop Web site to organize interactions with ideating consumers, and 3M has implemented a process of innovation rooted in co-creation. In a recursive process, ideation by 01 zwass.indd 25 10/6/2010 1:33:31 PM Twitter users leads to a continuing modification of the microblogging service. Idea competitions, ideation jams, and idea-generation markets are used to assess, and often generate, new product and market ideas. LEGO Design, Threadless.com, and Zazzle are exemplars of firms that involve users in product design, supporting them with toolkits available over the Web, and subsequently bringing the products to market. The evolving product offered by metaverses, notably Second Life, is developed largely by the users of the site. Initiatives of many kinds have been employed to draw in co-creating consumers. As one example, the labels contests for Jones Soda produce attractive photo-based designs-and a relationship with consumers. The beta testing of software by potential users has been joined by the testing of other products, with software prototypes and test kits available over the Web. Consumers contribute their computational resources to such grid-computing sites as SETI@Home and Folding@Home. Consumers' computers are used to transmit packets in the peer-to-peer systems of BitTorrent and Skype. Many firms have deployed eWOM in co-creation activities. Consumer-side production of ads, such as "flying iPods" and Sony's ad for Current TV, has produced not solely the ad designs, but also the eWOM. eWOM marketing programs have been organized, among other firms, by P&G with its Vocalpoint assembling 600,000 "connectors." P&G and Unilever have created Web sites for some of their personal hygiene products that have engendered communities of consumers who are more comfortable sharing their experiences and concerns with other members than with experts. P&G found these sites many times more effective than television advertising [25] . By uploading self-description, lifestyle documents, and photos to corporate Web sites, consumers offer the firm's marketers, with support from mining software and other software tools, an opportunity to obtain a rich picture of the 01 zwass.indd 26 10/6/2010 1:33:31 PM firm's customers. Thus, the Web site of Wet Seal, a 500-store clothing retailer, offers an Outfitter feature that allows users to produce virtual outfits on-line, to be shared with others, who comment on them. "We can get a read to where our customer is headed faster than ever before," states the firm's CEO [71] . Members of user communities are drawn upon by the producer firms to respond to questions and resolve use-oriented issues for other users. Requesting "help from the communities" is a well-known method of dealing with software problems-not infrequently used by employees of the producers as well. The development of a full-scale taxonomic classification of co-creation is a daunting task, considering the richness of the domain. As one relevant example, the rigorous systematics of organizations initiated by McKelvey has not been completed [74] . 8 Yet, the study of a research domain benefits greatly from the establishment of a classification of its entities in the theory-development work preliminary to further theory building [43] . Toward this end, the following taxonomic framework is offered, based on a multi-year study of e-commerce activity and of its analysis in the literature, both scholarly and anecdotal. The classification includes the most salient aspects of co-creation. It will undoubtedly be expanded in the future, both by scholarship and by events. It is hoped that further research in the area will lead to the refinement of this framework, with cluster analysis of its various segments, for example, aiming as it is at a moving target. The taxonomic framework is shown in Figure 2 . The typology of the co-created value is a part of it. The framework only includes aspects specific to co-creation. The Process characteristics are not taxonomized beyond Governance. The Incentives follow from the Motivation factors, discussed below. The IT support does not necessarily benefit from taxonomization. The specific, and vital, IT support includes, for example, prototyping aids, data-and text-mining systems, version-control systems for OSS, information markets, components for idea competition [65] , and myriad other systems. These are the components of the taxonomic framework. A task can be performed by any of the agent collectives listed below. • the world. Any individual can contribute to the best of his or her ability. This is well illustrated by the Wikipedia model, whose genius is its acceptance of the contribution of the provider of the mot juste as well as that of a highly credentialed creator of a scientific entry.
Zwass investigated the phenomena of co-creation REF and proposed a taxonomy of user-created digital content which includes the following: knowledge compendia, consumer reviews, multimedia content, blogs, mashups, virtual worlds.
Co-creation: Towards a taxonomy and an integrated research perspective
report | TNO 2012 R11277 Making User Created News Work 113 / 130 APPENDIX A – LIST OF PARTICIPANTS OF EXPERT WORKSHOP, INTERVIEWS AND ADVISORY GROUP WORKSHOP PARTICIPANTS Beukers, Jorien
Economics Computer Science