## 2 From Web 2.0 to Web 3.0
### Semantic Web  
The Web was designed and developed as an overall information space composed of distributed content. The current Web concept is perfectly suitable for human-machine interaction as well as for human-human communication. If the interaction model is extended to the machine-to-machine interaction (meaning machines would be able to understand, participate and help), the current information model, explicitly designed for human consumption, is one of the major obstacles to evolution. The Semantic Web approach develops languages for expressing information in a way machines can process. The Semantic Web is not a completely new understanding of the current Web. It is not a separate Web but an extension of the current concept, in which information is provided according to rich schemas that allow computers and people to work in cooperation [19]. Like the Internet, the Semantic Web will be as decentralized as possible [19]. Semantic technologies are partially inverting the common view of knowledge building and artificial intelligence. The common interaction model, which assumes intelligent actors working with the information, is radically changed in a new interaction model (semantic interaction): actors (that are understood as standard interpreters called reasoners) are able to process and understand rich data models as \"intelligence\" and are implicitly resident in the knowledge model itself. In other words, schemas contain information and the \"code\" to interpret it. This new view of the interaction model also implies a new understanding of interoperability (Semantic Interoperability). Semantic interoperability improves common interoperability models [20]: basic interoperability assumes the interchange of messages among systems without any interpretation [20]; functional interoperability integrates basic interoperability models with the ability of interpreting data in context under the assumption of a shared schema for accessing data fields [20]; semantic interoperability introduces the interpretation of the means of data [21; 22; 23]. Semantic interoperability is a concretely applicable interaction model under the assumption of adopting rich data models (mostly called Ontology) composed of concepts within a domain and the relationships among those concepts. As with the Web 2.0/Social Web, the Semantic Web concept [19] increasingly became very popular and it is considered one of the hottest research topics inside the scientific community. Due to its importance, a collaborative movement led by the World Wide Web Consortium (W3C) promotes common formats for data on the World Wide Web. By encouraging the inclusion of semantic content in web pages, the Semantic Web aims at converting the current web of unstructured documents into a \"web of data\" [10]. According to the W3C, \"The Semantic Web provides a common framework that allows data to be shared and reused across application, enterprise, and community boundaries.\"  
There are lots of similar definitions of semantic web available in literature. In 2001 [PERSON] proposed an intuitive definition for Semantic Web: \"The Semantic Web is an extension of the current Web in which information is given well-defined meaning, better enabling computers and people to work in co-operation\" [19]. Another definition approaching the technical solution is presented in [24]: \"The explicit representation of the semantics of data, accompanied with schema definitions, will enable a Web that provides a qualitatively new level of service\". In [25] the concept of interconnection of actionable information is added: \"The Semantic Web is a Web of actionable information, derived from data through a semantic theory for interpreting the symbols. The semantic theory provides an account of \"meaning\" in which logical connection of terms establishes interoperability among systems.\"  
Finally, in a more recent work [26], the idea of machine interpretation is included: \"The Semantic Web complements the current Web with machine process ability.