What does "catch 22" mean?

Catch-22 is derisive, historical novel written by American author Joseph Heller, it was published in 1961, the novel set during  the later stages of World War II 1944 onwards, it is one the great literary works of the twentieth century.

Catch 22 means that you can't win.  Within the book, "Catch-22" is a military rule, the self-contradictory circular logic that, for example, prevents anyone from avoiding combat missions.  If you don't want to fly missions, you are sane, and have to fly.  If you do want to fly missions, you fly them, even if you are crazy.