What is a script and how do I use one?

[Caper2]

I have a general idea on what they are like depositer but I don't know exactly what they are and how would I use them. Any help is appreciated, thanks.

[Infernal Bolt]

http://forums.xenobot.net/showthread.php?3362-How-to-open-a-.XBST-or-.LUA-file.