引述 :『Build critical mass on your website With so many websites to join, users must decide where to invest significant time in adding their same connections over and over. For developers, this means it is difficult to build successful web applications that hinge upon a critical mass of users for content and interaction. With the Social Graph API, developers can now utilize public connections their users have already created in other web services. It makes information about public connections between people easily available and useful. Only public data The API returns web addresses of public pages and publicly declared connections between them. The API cannot access non-public information, such as private profile pages or websites accessible to a limited group of friends. 』

引述 :『Nexus creates a graph of your social network and finds commonalities between your friends』

引述 :『In a nutshell, this is how Berners-Lee envisions the 3 levels (a.k.a. layers of abstraction): 1. The Internet: links computers 2. Web: links documents 3. Graph: links relationships between people and documents -- "the things documents are about" as Berners-Lee put it.』