Post-roll ads are advertisements that appear at the end of a video or audio content. They are designed to capture the audience's attention after they have engaged with the main content, often leading to higher viewer retention rates. These ads can be in various formats, including video clips, audio spots, or banners. Advertisers use post-roll ads to promote products or services, taking advantage of the audience's interest in the content they just consumed. This strategy can be effective for brands looking to reinforce their message or encourage immediate action, such as visiting a website or making a purchase.