Kruskal is a greedy_algorithm for building a minimum_spanning_tree of a weighted_undirected_graph. It sorts edges by weight and adds the next lightest edge that does not form a cycle, using a union_find data structure to check connectivity fast. Its time complexity is O(E_log_E) due to sorting, and it works well on sparse_graphs. Common uses include network design, road layout, and single-linkage clustering.