Connected components are subgraphs where any two vertices are connected by paths and disconnected from other graphs. The algorithm uses disjoint sets to determine if vertices are in the same component. Depth-first search (DFS) and breadth-first search (BFS) are common graph traversal algorithms. DFS uses a stack and visits the root node first before children. BFS uses a queue and visits nodes level-by-level starting from the root. Spanning trees connect all vertices without cycles, having n-1 edges for a graph with n vertices. Biconnected components are maximal subgraphs without articulation points whose removal would disconnect the graph.