Search algorithms use heuristics to guide the exploration of possible solutions in an attempt to find optimal solutions more efficiently than uninformed search methods. Heuristics estimate how close a state is to being a solution without calculating the actual distance, allowing algorithms like best-first search and A* search to prioritize expanding the most promising nodes first. Informed search algorithms like A* use an admissible heuristic that is guaranteed to never overestimate the cost to reach the goal, ensuring the search will eventually find an optimal solution if one exists.