## 2 The Concept and Use of Geographic Information Generated by Social Media's Users  
The widespread diffusion of tourism social media platforms could offer new opportunities for decision-support in tourism planning. Tourists' satisfaction depends on factors related to the location and the quality of services that the local tourist enterprises make available. Moreover, analysis of tourists' satisfaction may offer valuable knowledge in tourism planning at the regional and local levels. Here we propose an integrated approach to investigate, qualitatively and quantitatively, the relationships between tourists' satisfaction, geographic locations, and tourist enterprises in terms of support the tourism-related decision-making processes. The methodology implemented in the study includes data collection from the online tourism-related social networks Booking.com and TripAdvisor.com; that is, geographic information generated by social media's users, and integration of this information with authoritative territorial data, AuGI. The case study concerns the municipality of Cagliari and demonstrates the value of social media-related data integrated by authoritative information in tourism planning. We propose a critical discussion on the effectiveness of using the implemented integrated approach in order to address the definition of planning objectives in the context of SEA of MMPs. Social networks provide users with a collection of various interactive opportunities [12], ranging from simple chat to multiple video conferences, and from exchange of plain email messages to participation in blogs and discussion forums. Tourists have ubiquitous access to a broad range of information services. They visit the Internet to share information and communication, to shop online, to express views, and to keep online blogs [13,14]. The development of a shared knowledge base is the driving force of online communities and, as a consequence, social, economic, and technological aspects are incorporated into the online communities [15,16]. Moreover, developments in social media imply that every piece of information can be commented or rated in some way. Through interactive platforms participants, tourists in the case of TriAdvisor.com and Booking.com, share, co-create, discuss, and modify the generated geographic information [17, 18, 19]. Geographic information generated by social media's users may be geocoded in different ways [20], using either the positions of the authors (if available), or the locations of the posts (recorded, for example, through a GPS sensor of a mobile device), or through toponyms parsing in the posts' texts. Spatial data mining and geographic knowledge discovery are iterative processes that involve multiple steps, including data selection, cleaning, pre-processing, and transformation [20, 21, 22]. These methods are heuristic, inductive, and they include clustering, classification, rule mining, information visualization, and visual analysis [22]. They aim at integrating and further developing methods for the analysis of huge amounts of complex spatial data. TripAdvisor.com and Booking.com are among the most popular platforms that generate geographic information. They play a significant role in the online tourism market. They can be considered as market-driven social media [23]. Moreover, they assist tourists in posting and sharing their travel-related comments. Tourists' opinions and personal experiences based on reconstruction of their trips generate important information available to scholars who study tourism-related social and market dynamics. If information on the respondents' location is available, the information collected through tourism-related platforms is defined as volunteered geographic information (VGI). The term VGI has become popular to indicate the avalanche of information shared on the Web by users acting as sensors [24]. A frequently-discussed issue concerning user-generated content is the conceptual difference between explicit and implicit VGI [25, 26, 27].