An ad break (also called an avail, short for availability) is a slot in the content timeline reserved for advertising. In live and linear it is signaled in real time by SCTE-35 markers; in VOD it can be pre-defined at known points. The break has a duration that the ad system fills, often with a pod of multiple ads.
Breaks are where content and monetization meet, and their handling is full of edge cases: aligning the break to segment and keyframe boundaries for seamless insertion, deciding what to do if no ad fills the avail, and ensuring the content resumes cleanly afterward. Accurate avail signaling is the prerequisite for both SSAI and CSAI to monetize without disrupting playback.
