Lock a record so users can't edit it

Is there a simple way to lock records? for instance if a record has been finished with or invoiced and it just need to be archived for future reference, Is there away to lock the record so users can no longer edit it?

Thanks

That can probably be achieved with Security Groups, adding the record to a group that makes it read-only. I don’t know the specifics, it’s always a matter of trial and error with security settings.