AdWords Newbie Question

Please read and respond thanks! =)

[Eterion]

Hiya!
I just started using AdWords today (cuz I went live with my website today) and was wondering, what is an impression and do you get charged for these or only if the user clicks on your ad?
The Google glossary was very vague in defining this term.
Any help would be appreciated, thanks! =)

[inferno]

an impression is an ad view, basically if someone does a search for blue widget, and your ad shows up on that page, its considered an impression. u arent charged for them. welcome to the board mate! :)