:q to quit (short for :quit)
:q! to quit without saving (short for :quit!)
:wq to write and quit
:wq! to write and quit even if file has only read permission (if file does not have write permission: force write)
:x to write and quit (similar to :wq, but only write if there are changes)
:exit to write and exit (same as :x)
:qa to quit all (short for :quitall)
:cq to quit without saving and make Vim return non-zero error (i.e. exit with error)