Interesting. I've always liked "sign up", "sign in", and "sign out", because they were older and more widely used before computing. "Sign up" was used to refer

Interesting. I've always liked "sign up", "sign in", and "sign out", because they were older and more widely used before computing. "Sign up" was used to refer to subscribing, for example, to a magazine. "Sign in" and "sign out" were what they said for the guestbook at a hotel.