Network theory is a branch of applied mathematics, with the same general subject matter as graph theory, namely the idea of a graph as a representation of a symmetric relation, and of a directed graph for a general binary relation. The approach, though, is led by applications, in particular to computer networks but certainly not limited to those — for example a gene regulatory network may be modelled. See list of network theory topics for the scope of the area.

Network theory is also used to describe the use of social network maps within the social sciences. See social network for more information.