A social graph is a diagram that illustrates interconnections among people, groups and organizations in a social network. The term is also used to describe an individual's social network.
When portrayed as a map, a social graph appears as a set of network nodes that are connected by lines. Each node, which may also be referred to as an actor, is actually a data record. The connecting lines used to map relationships between data records are referred to as edges, ties or interdependencies.
When a social graph has a small number of nodes, it can easily be mapped on a whiteboard or piece of paper, using color-coded solid and dotted lines to indicate relationships. When the social graph has a large number of nodes, however, crisscrossed ties can quickly become tangled, making it difficult for anyone to get meaningful information out of the diagram. Graph database software such as Apache Giraph makes it easier to analyze a large, complex social graph database through queries. This is how most social media sites, including Facebook, use search algorithms to personalize news feeds and target advertising.
Facebook and social graphs
CEO Mark Zuckerberg is credited with first using the term "social graph" in 2007 to refer to the network of connections and relationships documented by Facebook members. Although Facebook provides third parties with limited access to members' social graphs through application programming interfaces (APIs), the site is often criticized for being a walled garden that constricts social graph portability, as well as the potential power of social graphs in general, by requiring members to recreate their social graphs manually in other applications.