There are a bunch of different ways to write files, to quit out of a Vim session, and to write and quit.
The standard is :wq to write to the file and quit. There is :xall which
will write changes to all buffers and quit.
:q, :q!, and ZQ—the latter being a normal mode command—are all ways of
quitting Vim. The first will warn of unsaved changes. The other two will
discard unsaved changes.
Another favorite of mine, when bailing on a git commit, is :cq.
These and more can be found in the help files by running :h Q_wq.