What does tab computer slang mean?

The tab button goes over a certain amount of spaces at a time so you don't have to push the space bar so many times. It also switches typing spaces, like if you have one box you can type in on the internet, like in your email, the username, for example, stevejobs@mac.com on the first line, and press tab, you can keep typing but in the passWord line, for example, ***.