Rollback

A rollback is the act of undoing a release, reverting your site to a previous version after a new one turns out to be broken.

Even with careful quality assurance, some bugs only show up once a change hits the live site. When a deployment goes badly wrong, you don't always have time to diagnose and fix it on the spot. Rolling back buys you that time: you restore the previous version, the site works again, and you sort out the problem away from the pressure of a live outage. This is one reason versioning and reliable backups matter so much, since a rollback is only possible if you kept a good copy of what came before.