The social graph is a term coined by scientists working in the social areas of graph theory. It has been described as "the global mapping of everybody and how they're related".^[1] The term was popularized at the Facebook f8 conference on May 24, 2007, when it was used to explain that the Facebook Platform, which was introduced at the same time, would benefit from the social graph by taking advantage of the relationships between individuals, that Facebook provides, to offer a richer online experience.^[2] The definition has been expanded to refer to a social graph of all Internet users.^[3]

A graph is an abstract concept used in discrete mathematics; the social graph describes the relationships between individuals online, as opposed to the concept of a social network, which describes relationships in the real world. The two concepts are very similar, but some minor differences do exist. For example, the social graph is digital, and more importantly, it is defined explicitly by all connections involved.^[3] Since explaining the concept of the social graph, Mark Zuckerberg, founder of Facebook, has often touted Facebook's goal of offering the website's social graph to other websites so that a user's relationships can be made aware and put to use on websites outside of Facebook's control.^[4]

A social graph is a sociogram which depicts all personal relations -- typically not more than 100 per person.

Issues

Several issues have come forward regarding the existing implementation of the social graph, particularly the one owned by Facebook. For example, currently, a social networking service is unaware of the relationships forged between individuals on a different service. This creates an online experience that is not seamless, and instead provides for a fragmented experience due to the lack of an openly available graph between services. In addition, existing services define relationships differently.^[3]

As of 2010^[update], the largest social graph in the world is Facebook's,^[5] which contains the largest number of defined relationships between the largest number of people among all websites due to the fact that it is the most widely used social networking service in the world.^[6] Concern has focused on the fact that Facebook's social graph is owned by the company and is not shared with other services, giving it a major advantage over other services and disallowing its users to take their graph with them to other services if they wish to do so, such as when a user is dissatisfied with Facebook.^[3] Google has attempted to offer a solution to this problem by creating the Social Graph API, released in January 2008,^[7] which allows websites to draw publicly available information about a person to form a portable identity of the individual, in order to represent a user's online identity.^[8] Facebook introduced its own Graph API at the 2010 f8 conference. The API allows websites to draw information about more objects than simply people, including photos, events, and pages, and their relationships between each other. This expands the social graph concept to more than just relationships between individuals and instead applies it to virtual non-human objects between individuals, as well.^[9]