Correct banner size is one of the most important choices that has to be made prior to throwing banners online. The following list shows the most common trends/sizes in banner advertising.
Always placed at top of the site, next to or just under title. Size: 468x60 / 728x90. A recent feature for Leaderboard banners is the slide down feature that increases the size and shifts the webpage content down.
Always placed left or right from web content but at top of the page. Size: 120x600.
Can be placed anywhere on a page, but most commonly is placed in center. Size: 250x250.
These are usually randomly positioned on web page and have a shape similar to Leaderboard. Size: 468x60.
A small banner, sometimes including text, randomly positioned on the web page. Sizes differ as to where advertorial is placed but commonly small. Size: 120x90.
Pop-ups (or pop-unders) come up by entering or selecting a particular web page. They have to be closed to get to the web page. Pop-unders will show once the site is closed. Size: often square, mostly are 550x480.
Very similar to Pop-under, as it will appear once the web page is closed. Sizes differ but larger than Leaderboards.