The document discusses various search algorithms such as best-first search, A* search, hill-climbing search, and forgetful hill-climbing search. It explains that A* search combines the cost so far with a heuristic estimate of the remaining cost to provide an optimal path. The heuristic must be admissible, meaning it cannot overestimate the cost to the goal. With an admissible heuristic, A* search is proven to always find an optimal solution.