What do you mean by Ad rotation?

Ad rotation is the technique of displaying several advertisements on a web page at the same time. With each new page load, during a single page load, or both, advertisements may cycle. The advertising often have the same format because they are displayed in the same spot. 

The method of showing multiple advertising on a website at once is known as ad rotation. Ads may cycle on a single page, on subsequent page loads, or on both. Due to their placement, advertisements frequently follow the same format.