The audit log

Every create, edit, delete, void and override, with before-and-after values.

Settings → Audit log.

Every create, edit, delete, void and permission override is recorded with who did it, when, from where, and — for edits — the value before and after.

It cannot be switched off or edited. That is what makes it an audit log rather than an activity feed.

Related exception reports: Voided/Deleted Transactions, Closing Date Exceptions, Transactions without Class, Missing Check Numbers, and Duplicate Detection.