Regression testing
Also called: regression, regression pack, regression suite
Regression testing re-checks behaviour that already worked, to confirm a change has not broken it.
Regression testing confirms that what worked before a change still works after it. It is different from testing the change itself: the question is what else moved.
Full regression every sprint is rarely possible, and trying to do it usually means doing it badly. The practical approach has two layers. A small core of journeys that carry revenue, compliance or trust is re-checked every release. Around that, the scope follows the change: which code, configuration and integrations moved, and which journeys they can reach.
Automation is well suited to the core, because those checks are understood and repeated. People explore around the change. Anything left out is written into the readiness note as deferred, with a reason and an owner, so the gap is a decision and not an accident.