Social network theory examines relationships between individuals and groups through attributes like information exchange, tie strength, and flow of resources. Social network analysis uses tools from graph theory and sociology to study patterns of information exchange in human networks. It provides insights into identifying and modifying information flow, as well as cohesive groups and key information brokers. Milestone studies include Milgram's small world experiment showing six degrees of separation and Watts' work confirming small path lengths in human networks.