Compositing is the browser step that merges many page layers—text, images, video, overlays, animations, and UI elements—into the final frame you see on screen. It is part of the rendering pipeline, but it is not just a visual feature: it also handles timing, memory, and coordination with graphics hardware.
In cyber security, compositing matters because it processes untrusted web content at high speed and often sits near complex graphics code. Bugs in this area can cause crashes, screen corruption, information disclosure, or memory-safety flaws that attackers may try to turn into code execution. It is also a useful defense point: browsers harden compositing to isolate tabs, validate layer data, and limit how malformed content reaches lower-level graphics APIs.