Apple's Garageband is a Digital Audio Workstation(or DAW if your a virgin)by Emagic, used by most people to pollute eardrums with poorly written and recorded music to try and impress arty chicks.
While the Apple computer offer a okayish microphone built in, trying to write, arrange and record a good song is like trying to get high of feces: its degrading, frustrating, pretty much impossible and causes the abandoment of everyone you love.
The thing that makes this program so awful yet so popular is simple: Apple loves to dumb down everything. After purchasing Emagic, the company that makes garageband, They decided the best use of their technological expertise was to basterdize their flagship software (Logic) into a free, halfass program to cash in on American Idol wannabees everywhere.
You see, The trouble lies in the fact that, in order to arrange and compose high quality music, you need extensive control and tools that take time to learn and master. This can't happen when everything has to be simple enough for a toaster to operate.
To compromise, Emagic threw in a ton of "Apple Loops" so people can arrange music other people deem to worthless to actually make songs out of! they then proceeded to overcharge for these and profit grossly.
The result is that tons of foolish, star-eyed children (yet to be crushed by the soberity of life) and a bunch of arrogant tools thinking that all they need is a macbook to be on their way to stardom. They are soon laughed out the room by people who know what the hell their doing.
Despite this, said tools may still get laid.