VIM

Hit the Esc key to enter "Normal mode". Then you can type : to enter "Command-line mode". A colon (:) will appear at the bottom of the screen and you can type in one of the following commands. To execute a command, press the Enter key.

    :q to quit (short for :quit)
    :q! to quit without saving (short for :quit!)
    :wq to write and quit
    :wq! to write and quit, attempting to force the write if the file lacks write permission
    :x to write and quit; like :wq but writes only if modified (short for :exit)
    :qa to quit all (short for :quitall)
    :cq to quit, without saving, with a nonzero exit code to indicate failure (short for :cquit)

You can also quit Vim directly from "Normal mode" by typing ZZ to save and quit (same as :x) or ZQ to just quit (same as :q!). (Note that case is important here. ZZ and zz do not mean the same thing.)

Vim has extensive help - that you can access with the :help command - where you can find answers to all your questions and a tutorial for beginners.