What does "Catch-22" mean?

A no-win dilemma or paradox, similar to damned if I do, damned if I don't. For example, You can't get a job without experience, but you can't get experience unless you have a job—it's Catch-22. The term gained currency as the title of a 1961 war novel by Joseph Heller, who referred to an Air Force rule whereby a pilot continuing to fly combat missions without asking for relief is regarded as insane, but is considered sane enough to continue flying if he does make such a request.