Leader Board Banner Ad (728 by 90 pixels)
Leader Board banners generally are included at the top of a website for maximum exposure and are the largest size to you get the most advertising area for you dollar.
Standard Banner Ad (468 by 60 pixels)
Standard banner ads where the first size of banner advertising used so there are a significant number of sites that only use the standard banners size. It can be placed in several different spots throughout a site.
Medium Rectangle Ad (300 by 250 pixels)
Medium rectangle ads are generally placed within the body of a website. This makes them particularly effective since they are positioned among text or images that visitors are viewing or reading.
Wide Skyscraper Ad (160 by 600 pixels)
Like the leaderboard ad, Wide skyscraper ads cover a lot of area due to their large size. They are typically placed flush left or flush right on the screen which puts them very close to navigation bars and other areas where they are sure to be noticed.
