Acronym for the “Bourne Again SHell,” a clever play on words referring to the old “sh”, which was the “Bourne SHell,” named for its inventor. It’s the default command shell for many Unixes, including Mac OS X (Panther and later), and Linux.

For people coming from DOS and Windows, bash has an extremely rich “batch” language which allows for lots of scripting power.

Tips

CTRL-X, CTRL-E — opens the current command line in $EDITOR (vim for me, of course) for editing