1. A computer implemented method of identifying a cohesive user group in a social network for delivery of a tailored content item, the method comprising: identifying first affinity criteria comprising at least one of a first interest category and a first personal attribute classification; accessing one or more databases of information for a social network, the information comprising a plurality of user identifiers, each user identifier associated with data for personal attribute and interest characteristics and social network user connections; generating, using one or more computer processors, a first set of user identifiers, by processing data obtained from the one or more databases such that the first set is limited to user identifiers associated with characteristics that satisfy the first affinity criteria; generating a graph representative of social network user connections comprising a plurality of nodes and a plurality of edges, wherein each node represents a user identifier from the first set of user identifiers and each edge connects a pair of nodes and is one of a direct-connection edge representing a direct social network user connection between each user identifier represented by the respective pair of nodes connected by the edge and an indirect-connection edge representing an indirect social network user connection between each user identifier represented by the respective pair of nodes connected by the edge; generating, using the one or more computer processors, a sub-graph of the graph, wherein each edge of the sub-graph satisfies selected edge criteria; and storing, on computer readable media, data representing the edges of the sub-graph.