Drum machines are great for musicians who want to play along to a beat while practicing, but without having an actual drummer there. Many pianists, keyboardists, bassists, guitarists, etc. use them for this purpose.

Drum machines (and grooveboxes) are special units that only contain drum sounds in them (usually). The drum machines have an internal sequencer that allows you to program in a drum song, and play it back. This makes drum machines nice for people who have a limited amount of musicians: You can pre-record and play back rhythm parts while you play back live on top of them. Drum machines also have a special charm in rap and hip-hop music, due to the more "electronic" sound a drum machine has and the fact that it is able to keep a beat perfectly.

There are several types of drum machines available. Very old drum machines use analog synthesis as a way to make drum sounds. Later, drum machines started using digital samples to make the sounds, although some machines exist that use both methods. Nowadays, almost all drum machines on the market are sample-based. A few drum machines, however, allow you to load your own samples in to be used as rhythms, thus opening up another dimension of rhythms. Some drum machines nowadays are modeled after analog.