What is the purpose of the stp protocol?

Answer 1

The STP protocol allows switches to have redundant connections, while avoiding problems associated with switching loops. For example, if there is a switching loop, a broadcast would go around in circles indefinitely. There are other problems, too. The STP protocol disables enough connections so that there are no loops; the disabled connections are in "stand-by" and can be enabled again when other connections fail, thus providing the desired redundancy.