Read the first three pages in order before any write to versioned content: how a record keeps its content in revisions and which one is live, which of the three write shapes to send (a patch, a full set of revisions, or an edit of one revision by id), and how a revision goes live, rolls back and is published. Choosing the right one of these keeps every write predictable.

The rest answer one question each, and can be read when you need them: the write shape of each input type, editing one element of a component collection, custom fields, custom URLs and slugs, and what to do when a write timed out and may have applied. The examples are real responses from this site's API sandbox records. The endpoints themselves are in the API reference.