Above the Fold  -  Above the fold is a term used for the area of a webpage that displays without having to scroll.

Ad  -  Short for advertisement, an ad is a message which is conveyed to an existing or potential customer.

Ad Inventory  -  Ad Inventory is the total amount of ad space available on a website.

Ad Placement  -  An ad placement is a way to place an ad or group of ads on a site.

Ad Rotator  -  An ad rotator is a computer system that rotates the order or relative position in which a set of ads are displayed.

Ad Tag  -  An ad tag is an html tag that is placed in your source code in the location where you want ads to appear.

Ad Zone  -  An ad zone is a region on a page in which ads display.

Advertisement  -  Advertisement is the long form term for Ad (see Ad).

Banner Rotator  -  A banner rotator is a system that rotates a set of banner ads in and out of a single spot on a website (usually the header/leaderboard).

Below the Fold  -  Below the fold is a term used for the area of a webpage that displays only after you scroll down.

Impression  -  A basic ad impression occurs any time an ad is served.