A loop, in its simplest form, is a piece of music that can repeat (loop) seamlessly. Loops are designed this way; a good one can be repeated without missing a beat. When you repeat a loop in music recording, it's called looping. GarageBand has two kinds of loops:

• Software instrument loops: These are recorded using a MIDI keyboard or drum machine. Most of the loops that come with GarageBand are software instrument loops.
• Real instrument loops: These are recorded from an analog source (that is, real musical instruments). You don't find many of these in GarageBand.

Entire music genres -- dance, electronica, house, rap, and many others -- have made an art form out of using loops. But don't let these genres limit your perception of how loops are used. In GarageBand, loops don't always have to be looped. In fact, many of GarageBand's loops sound better as a one-shot accent than they do when you loop (repeat) them more than once. Here are a few possibilities:

• Loops are often used as a background groove or as the central, driving theme of a song. You can use a drum loop to provide the backbeat to your song or maybe just to keep the beat while you build other tracks with loops, instruments, and vocals.
• Loops can also be used as musical punctuation marks. You can make a horn part lurk in the chorus, or a funky guitar riff chug along in the verse.
• You can also use a loop to spice up a single chorus, bridge, or verse and make it just a little bit different than the others ones. You can add a shaker or other percussion loop in the last verse and find that that was exactly what was missing in the song.