Where aparcaran my guests if I buy a house in San Francisco? The daily commute to work in San Francisco worth it to live in Palo Alto? What is the normal price of a garage in Pacific Heights plaza? These questions, together with their answers, are a small sample of common content in the last batch of real estate portals that have signed up to new trends in what has been called the Web 2.0: all a fresh and revolutionary way of understanding what is the Internet and how to leverage the full potential of the network communication. Users asking or responding to other users in a common meeting point: the real estate portal, which turns through this constant supply of content by its visitors and the integration of information and functionalities of other portals, a very powerful tool at the service of a more documented decision of buying or selling in the most important commercial transaction that most people perform to the length of your life: their housing-related. But what is Web 2.0? The Web 2.0 term is coined by Tim O’Reilly in 2004 to refer to a second generation of web sites characterized by greater interaction with and among users, which aims to facilitate creativity, collaboration and sharing of information between users. No refers both to a new language or nor a new Protocol, but to a new way to understand the Web and take advantage of all its features. If first generation web sites were characterized by a creation and dissemination centralized content companies decided what they wanted to include in their web sites, created the contents and functionalities, and published their pages through a web hosting spreading them, as a maximum, through newsletters and bulletins, web 2.0 sites are characterized, above all, by the integration of content and functionalities of other portals (for example(, Google Maps, Google Earth, YouTube, etc.) and because Users acquire a leading role by providing multiple ways of generating a feedback or feedback that integrates, as additional content, the development of the web site itself, enriching it. .