How do I unblock someone on Facebook? Blocked them in anger and regret it now.

Go to Settings & Privacy > Settings > Blocking (on mobile, search 'Blocking' in settings). You'll see your Blocked list, tap Unblock next to their name and confirm. Important: unblocking does NOT re-add them as a friend, you'll have to send a fresh friend request. Also, you can't re-block them for 48 hours after unblocking, so be sure before you do it.

The 'not friends again' part surprises people. Unblocking just lets you see and contact each other, the friendship is gone, so you'll need to re-send the request.

Heads up on the 48-hour rule, once you unblock you can't block them again for two days. Facebook does that to stop block/unblock spam.