Tim Berners-Lee

Facebook, LinkedIn, Friendster and others typically provide value by capturing information as you enter it: your birthday, your e-mail address, your likes, and links indicating who is friends with whom and who is in which photograph. The sites assemble these bits of data into brilliant databases and reuse the information to provide value-added service—but only within their sites. Once you enter your data into one of these services, you cannot easily use them on another site. Each site is a silo, walled off from the others. Yes, your site’s pages are on the Web, but your data are not. You can access a Web page about a list of people you have created in one site, but you cannot send that list, or items from it, to another site. The isolation occurs because each piece of information does not have a URI. Connections among data exist only within a site. So the more you enter, the more you become locked in. Your social-networking site becomes a central platform—a closed silo of content, and one that does not give you full control over your information in it. The more this kind of architecture gains widespread use, the more the Web becomes fragmented, and the less we enjoy a single, universal information space. A related danger is that one social-networking site—or one search engine or one browser—gets so big that it becomes a monopoly, which tends to limit innovation. (2010) source Verified