Community detection is a research area in network analysis that involves identifying groups of nodes in a network that are more densely connected to each other than to nodes in other parts of the network. These groups are known as communities, and detecting them can provide valuable insights into the structure and function of a network. There are various algorithms and methods used for community detection, including modularity optimization, spectral clustering, and stochastic block models. Community detection has applications in social networks, biology, and computer science, among other fields.