Chapters

Chapters are yours to define. Put timestamps in the description, start the list at 00:00, give it at least three entries in ascending order, and keep every chapter to a minimum of ten seconds; YouTube then splits the progress bar into named segments viewers can jump between. Automatic chapters, also called key moments, are the separate thing YouTube generates by itself when a video has none, and the two get confused constantly. Adding your own overrides them. Chapters suit tutorials, reviews and anything long enough that people arrive looking for one part of it.