In this chapter, we discussed different searching algorithms and their complexities. You learned how to improve searching with a hash table to get a constant time result. We also explored BFS and DFS, two of the most important methods for hierarchical data searching. We will use similar concepts for graph data structure, which we are about to explore in the next chapter. Graph algorithms are crucial for solving many problems and are used heavily in the programming world. Let's get going with another interesting topic - the graph.