What is Spanning Tree?

A tree is a no cycle, connected undirected graph. It would be a spanning tree of a graph G if it includes every vertex of G or spans G. It would be a subgraph of G if every edge present in the tree belongs to G. A spanning tree of a connected graph G can also be defined as a maximal set of edges of G which actually contains no cycle, or it could be the minimal set of edges that would connect all vertices. Technically, a graph, which is not connected, will never contain a spanning tree but possible to have several spanning trees.