When to use “join,” “register,” or “sign up”?

Question

For a user, when is it better to be asked to do the following:

1. "Sign In" vs. "Log in"
2. "Join" vs. "Register" vs. "Sign Up"
3. "Sign Out" vs. "Log out"

Different websites seem to use them differently, and I wonder if there are strategic occasions for each?

Answer 1

Log in / out is more technical sounding than sign in / out. That said, I don't think there is any confusion with either one of them. The last time I looked at major sites using log v. sign it was a pretty even split between them. I would opt for sign in / out simply because it is more human speak.

Regarding Join, Register and Sign up. They each have slightly different meanings language wise, although even here I doubt that it will be critical.

For my (arguably subjective) take on their meanings:

• Join is when it's a club. You join a rowing club.
• Register is used when you are simply adding your details to some system for future use or access. You register to vote.
• Sign up usually has the connotation of a service or conference. You sign up for the military, or sign up for this conference.

The best thing that you can do is to ask a representative sample of your audience what is clearer and more human to them. Then go with that.

Edit: Something to consider is using "Sign up" and "Log in" as they are further apart visually and faster to scan than using "Sign up" and "Sign in".