A greedy algorithm builds a solution step by step by making the locally optimal choice at each stage. The hope is that by choosing the best immediate option, the algorithm will eventually arrive at a globally optimal solution. Greedy algorithms are used in problems like the knapsack problem, activity selection, and Dijkstra’s shortest path algorithm. However, greedy algorithms do not always produce the optimal solution, so it’s important to ensure the problem satisfies the greedy-choice property and optimal substructure before applying a greedy approach. When these conditions hold, greedy algorithms are often very efficient.