Explanation of minimal spanning tree

The table below shows the order in which nodes are added to the minimal spanning tree rooted at node 0. In each iteration, a new node is added to the tree, and the distance to that node from all nodes adjacent to it are updated. Refresh the page to see another randomly generated unweighted graph.

0123456789
0infinfinfinfinfinfinfinfinf
0infinf5infinf17infinfinf
019inf5infinf17infinfinf
09125infinf17inf15inf
09851517inf12inf
09851517inf124
09851517inf34
09851517inf34
09851517inf34
09851517134