As the average computer screen size

As the average computer screen size has grown larger, the size of online advertisements as grown as well. The leaderboard ad, which was introduced in 2003, has a standard size of 728 pixels wide by 90 pixels tall (728x90). Compare that to its predecessor, the banner ad, which is 468 pixels wide by 60 pixels tall (468x60).
Leaderboards can contain text, images, or even animations. When a visitor clicks on a leaderboard, he or she is directed to the advertiser's website. While leaderboards are larger than the original banner ads, most Web developers have found ways to incorporate the ads in ways that are not too distracting to the user.