You know kitty, there is a closely guarded secret to finding answers to those types of questions on the internet. Since I'm a nice guy I'll give you a link to it.
Closely guarded secret. I don't mean to be sarcastic (wait, yes I do) but you have to try that before you post. I think this page has a good difinition:
http://www.webopedia.com/TERM/P/PING.html Good luck.
deepblue