Semantics and Experience in the Future Web Enric Plaza IIIA, Artificial Intelligence Research Institute CSIC, Spanish Council for Scientific Research Campus UAB, Bellaterra, Catalonia (Spain) enric@iiia.csic.es Abstract. The Web is a vibrant environment for innovation in com- puter science, AI, and social interaction; these innovations come in such great number and speed that it is unlikely to follow them. This paper will focus on some emerging aspects on the web that are an opportunity and challenge for Case-based Reasoning, specifically the large amount of experiences that individual people share in the Web. The talk will try to characterize this experiences, these bits of practical knowledge that go from simple but practical facts to complex problem solving descriptions. Then, I’ll focus on how CBR ideas could be brought to bear in sharing and reusing this experiential knowledge, and finally on the challenging issues that have to be addressed for that purpose. 1 Introduction The Web is a vibrant environment for innovation in computer science, AI, and social interaction; these innovations come in such great number and speed that it is unlikely to follow them. This paper will focus on some emerging aspects on the web that are an opportunity and challenge for Case-based Reasoning, specifically the large amount of experiences that individual people share in the Web. These experiences, ranging from client reports on hotels they have visited to small explanations on how to do certain things, are searched for and reused by thousands of people. These experiences can be found in forums and blogs, in normal web pages and in specialized services like Question-Answer websites. However, they are treated documents, not as experiences. That is to say, they are represented, organized, analyzed, and retrieved as any other document. The main purpose of this paper is to argue that there is a special kind of content, namely experiences, that provides a specific form of knowledge, experiential knowledge, and they should be represented, organized, analyzed, and retrieved in accordance to this nature. Moreover, the paper will provide some food for thought by proposing some ideas on the conditions required and the techniques suitable to build systems capable of reusing experiential knowledge provided by other people in specific domains. The structure of this paper is as follows. Sections 2 and 3 discuss two of the most noteworthy components of current debate on the web, namely adding a semantic substrate to the web (e.g. the semantic web, folksonomies) and the K.-D. Althoff et al. (Eds.): ECCBR 2008, LNAI 5239, pp. 44–58, 2008. c  Springer-Verlag Berlin Heidelberg 2008