Rotation

Detailed explanation

Rotation is a delivery method in which more than one ad creative — or more than one advertiser — shares a single ad slot, with the ad server alternating which one appears according to a predefined ratio or share. For example, three creatives set to rotate 50/30/20 will each appear roughly that percentage of the time a given slot is served, rather than any one of them appearing every time.

Rotation is the standard way ad servers make efficient use of a limited number of premium slots: instead of dedicating a valuable position to a single fixed advertiser (as in a fixed placement deal), the publisher can sell that same position to several advertisers simultaneously, increasing overall fill and revenue from the same inventory. It is also used within a single advertiser's own campaign to A/B test multiple creative variations, letting the advertiser compare performance across versions while they run concurrently in the same placement.

Because rotation splits exposure across multiple creatives, individual advertisers in a rotation naturally receive lower total impression volume and visibility per campaign than they would with a fixed placement — a trade-off that is reflected in rotation inventory typically being priced lower than exclusive, guaranteed placements.