A reveal (or uncover) is where the new screen is **already underneath** and the old one is removed. It is a cover played backwards — the motion you use when dismissing a modal is effectively a reveal. Keynote calls it "Reveal", PowerPoint "Uncover".
Because the new screen has been in place all along, the eye does not have to chase anything; it feels like lifting a lid to find what was there. It matches meanings of **resolution**: close, done, go back.
It looks like a wipe (→ wipe-transition), but a wipe **cuts** the new screen into view along an edge, whereas in a reveal the whole old screen **moves away**.
When to use
Use it for dismissing modals and sheets or returning after a task. Cover to open, reveal to close — they are a pair.