Kruskal's algorithm is an algorithm of graph theory that constructs the minimum spanning tree of a graph by adding edges to the spanning tree one-by-one. At all points during its execution the set of edges selected by Kruskal's algorithm forms a forest of trees. The steps in this algorithm can be seen here http://students.ceid.upatras.gr/~papagel/project/pseukrus.htm
Kruskal's algorithm is conceptually quite simple. The edges are selected and added to the spanning tree in increasing order of their weights. An edge is added to the tree only if it does not create a cycle.
Java applet demos of Kruskal's algorithm can be seen here http://www.unf.edu/~wkloster/foundations/KruskalApplet/KruskalApplet.htm http://students.ceid.upatras.gr/~papagel/project/kruskal.htm