How to Respond to "Thank You"?

Most languages have an automatic response to thanks.
The British don't automatically respond to thanks, but Americans do. A response is not necessary in British English, but is becoming more frequent.

Some of the ways of responding to thanks are:
You're welcome. (mainly US)
Not at all. (Formal, UK)
It's my pleasure.
Don't mention it.
Any time.
That's alright/okay.
No problem.