What is a beta version when talking about video games

A beta version when talking about video games, is an incomplete version of the game that still my have glitchs or bugs in its running system.  you maybe able to make it so you are not on the map or there may be enemies that are not in the real full version. there maybe less levels or enemies may not attack you, some enemies  may not be able to be killed, Etc. There may be large amounts of enemies in one area that don't move, don't die or do any thing at all but slow you down.