The Semantic Web project, developed and promoted by the W3 Consortium, an international consortium that guides the development of the Web, of a brilliant idea: what if the web pages could be processed as input to computer programs and not just as something meant to be displayed to be seen by a human being? It could be great things. Current Web 2.0 is certainly not the Semantic Web, but almost everyone acknowledges that it has brought dramatic changes and could be a good example of what we might expect. What we need to move from the Web as a document (the current Web) as data to the Web (Semantic Web) is that, first, page, plus content for humans (information), including content for computers (metadata). However, the Web has universal scope, so we need metadata systems (or metainformaciones) suitable for universal use and interpretable by computers. Second, we need some sort of formal or superclasificaciones supertesauros (ontologies) that help computers to make valid inferences about the data. Eventually, software agents, representing users could successfully carry tasks for which now requires intelligence, that is, tasks that people can only run successfully today. In this work we present an overview on the proposed semantic Web and its various components. In the early chapters a global vision that seeks to show the different views of the semantic Web is presented. In the rest of the work the authors have sought to adhere to the current and future potential of the Semantic Web, understood primarily in relation to its impact on the level of information systems. As a general background of the work, has attempted to consider the kind of needs, tasks and objectives that are often professionals, scholars and researchers of documentary information systems. If the authors and publishers of this book share some common ideas, these consist of the belief that the group of library professionals-documentation should not only know the design of the World Wide Web Consortium, but has to be part of their protagonists, and all the new ideas, conceptual models, standards, recommendations or languages ​​of the Semantic Web is bound to have a lasting influence on many aspects of library-documentation, which brings us back to the first idea: to our collective role that can and should play in the project of the Semantic web. That is, in all modesty, but complex, the aspiration of this work.