GarageBand

GarageBand is a music creation software that has a recording studio and an express mode. When recording real instruments GarageBand has loads of effects to make the instrument sound it's best.

GarageBand '11 (with iLife '11) now comes with one lesson in each instrument with more available for $4.99 each. GarageBand is the little brother to Logic Studio which is the top of the music department (Logic Express is in the middle). Extra GarageBand Loop Packs are available to add to the collection of in-built items.

Versions
GarageBand has evolved but now it's pretty stable so not much is changing.

Version 1.0
GarageBand was made by Emagic just after they were bought by Apple who also make Logic Studio. It was announced at MacWorld '04 by Steve Jobs.

Version 2
Version 2 was released the following year at the MacWorld '05. This had a ton of new features, making it 100% Apple. Major new features included to be able view and edit music in Musical Notation form, record up to 8 tracks at once, fix timing and pitch of recordings, automate track pan position, master volume and pitch, work with MIDI files.

Version 3
Version 3 was released at the next MacWorld. This featured podcast creation which involves integrating iChat and having over 200 effects and jingles available.

Version 4
Version 4 was released as part of iLife '08. This featured to be able to record parts of songs, make iPhone ringtones and Magic GarageBand where you can easily make a song (mainly cheating, unless you do parts yourself)

Version 5
Version 5 is a version which comes with iLife '09. This features new videos and to be able to buy them. For guitar players you could now use your mac as an amp and pick which one you want.