Sizes in bold are part of the IAB's Universal Ad Package.

Name	Width / px	Height / px	Aspect ratio
Rectangles and Pop-Ups
Medium Rectangle	300	250	1.2
Square Pop-Up	250	250	1
Vertical Rectangle	240	400	1.67
Large Rectangle	336	280	1.2
Rectangle	180	150	1.2
3:1 Rectangle	300	100	3
Pop-Under	720	300	2.4
Banners and Buttons
Full banner	468	60	7.8
Half banner	234	60	3.9
Micro bar	88	31	2.84
Button 1	120	90	1.33
Button 2	120	60	2
Vertical banner	120	240	2
Square button	125	125	1
Leaderboard	728	90	8.09
Skyscrapers
Wide skyscraper	160	600	3.75
Skyscraper	120	600	5
Half page ad	300	600	2

 

The advertisement is constructed from an image (GIF, Flash, often employing animation, sound, or video to maximize presence). Images are usually in a high-aspect ratio shape (i.e. either wide and short, or tall and narrow) hence the reference to banners. These images are usually placed on web pages that have interesting content, such as a newspaper article or an opinion piece. Affiliates earn money usually on a CPC (cost per click) basis. For every unique user click on the ad, the affiliate earns money. Typical web banner,

The web banner is displayed when a web page that references the banner is loaded into a web browser. This event is known as an "impression". When the viewer clicks on the banner, the viewer is directed to the website advertised in the banner. This event is known as a "click through". In many cases, banners are delivered by a central ad server.

When the advertiser scans their logfiles and detects that a web user has visited the advertiser's site from the content site by clicking on the banner ad, the advertiser sends the content provider some small amount of money (usually around five to ten US cents).[citation needed] This payback system is often how the content provider is able to pay for the Internet access to supply the content in the first place. Usually though, advertisers use ad networks to serve their advertisements, resulting in a revshare system and higher quality ad placement.