Part of macOS

`opendirectoryd`User accounts

○ Leave it

Looks after user accounts and sign-in details.

What it is

Answers questions about users and groups on the Mac.

If you stop it

macOS starts it again straight away. Leave it.

○ Leave it. Part of macOS, or something that starts again by itself. You never need to close these.

From Procession’s guide, in the words the app shows.