The document describes the steps of performing a breadth-first search (BFS) on a graph. It shows the graph being traversed level-by-level with nodes placed in a FIFO queue. As nodes are dequeued from the front of the queue, their unvisited neighbors are discovered, marked as visited, and added to the back of the queue. This process continues until the queue is empty, indicating all nodes reachable from the source have been visited.