A button on the left side of your keyboard. When you are wordprocessing, it is mainly used to cause an indentation in the text. Depending on your software, it could create a constant-length space, or simply move your cursor to the next tab-index.

Also functions to move your cursor along the various tab stops of the current Windows application. Much confusion results when users attempt to cause an indentation while typing only to find that their cursor has disappeared into the ether.

Can also serve to bring up the automap in a lot of games.

It is also something I pried off of my keyboard and gave to my friend Tabitha.