Leaderboard is a standard web banner size. As the average computer screen size has grown, so have the size of online advertisements.
The banner ad, introduced in 2003, has a standard size of 728 pixels wide by 90 pixels high (728x90). Compare this to the previous ad banner ad at 468 pixels wide by 60 pixels tall (468x60).
Leaderboards can contain text, images, and even animations. When a visitor clicks on a leaderboard, he or she is taken to the advertiser's website.
Even though the leaderboards are larger than the original banner ads, most Web developers have found ways to combine the ads in a way that doesn't distract the user too much.
A leaderboard ad is especially good for expandable ads, as their usual top-middle positioning on a website means that they can expand in a practical manner. They are also often used when other bits of advertising code needs to piggyback onto a page, as they generally load first.
The unit still frequently shares an ad slot with the now-defunct 468×60, which is commonly served through a multi-size ad slot.
For more information about the image sizes you can check out our blog;