Straight from the 7 essential meta questions of every beta:
Imagine you’ve just gotten on an elevator with a friendly stranger. You have precisely one floor to describe your community to them. What would you say? The elevator pitch is a brief sentence that describes what your site is about. Every word counts!
Once decided, it can be sliced and diced to form:
- the tagline
- the motto
- the blurb under the logo
- a convenience redirect “nickname” for the site
- perhaps eventually the domain name in some form
(Due to a variety of practical difficulties with domain names, we prefer to de-emphasize domain name selection. Most sites will retain their topic.stackexchange.com names indefinitely.)
Naming is hard — really hard. But if you can come up with a sensible elevator pitch for your community, it’s a great starting point.
For more detail see: Stack Exchange Naming for Dummies