The Louvain method is a popular algorithm used for detecting communities in large networks. It optimizes the modularity of a network, which measures the strength of division of a network into communities. By grouping nodes that are more densely connected to each other than to the rest of the network, the Louvain method helps identify clusters or communities within complex data structures. This method operates in two main phases: first, it assigns each node to its own community and then iteratively merges communities to maximize modularity. The Louvain method is widely used in various fields, including social network analysis and biology, due to its efficiency and scalability.