The document discusses depth first search (DFS), an algorithm for traversing or searching trees or graphs. It begins with an introduction to DFS, explaining that it explores edges out of the most recently discovered vertex as deep as possible before backtracking. It then provides pseudocode for the DFS algorithm and explains that it has a time complexity of O(V+E), where V is the number of vertices and E is the number of edges. Finally, it lists some applications of DFS such as cycle detection, solving mazes, and analyzing networks.