What is it for?
A banner is a display of an image on a website.
jpg, png, gif, jpeg
Recommended weight per image
Between 50 and 300kB.
Define the banner sizes that will be needed for publishers. We recommend that you start by planning the IAB* sizes (see below) which are the most commonly used by publishers. As you go along, you may need to add specific formats on request from publishers.
Getting the ad by publishers
By using the same sizes throughout the life of a campaign, publishers do not need to retrieve the new tracking each time as the update is automatic (see the article here, step 3: replacement).