A drum machine is an electronic device which imitates the sound of various percussion instruments, most notably drums. These machines are generally programmed by indicating which sixteenth count a given percussion instrument will sound on.

The earliest drum machines were referred to as rhythm machines, because they could not be programmed to play individual beats but came with preprogrammed rhythms, such as tango and mambo.

Patterns such as fills, breaks, rhythmic changes, and longer phrases can be programmed by putting differently programmed bars together. Among the standard drum machine controls, which can often also be controlled through MIDI, are start and stop, tempo, individual sound volume controls, individual drum sound keys, and memory space for different drum patterns.

The concept of having a mechanical rhythm device has been in use for over a century, but these devices were always used to help musicians keep time, and were never meant for performances. The earliest drum machines were attached to electric organs, designed to add spice to home performances, and were later expanded on to help small-time musicians find a substitute for live drummers.

These early machines, which came with certain preset rhythms, often sounded very little like the drums they were supposed to be imitating. The first drum machines which did not have preset patterns but could be programmed, became available in the mid 1970s, when the technology for digital music took a leap forward. The first programmable drum machine, which coincidentally was also the first stand-alone drum machine, was the PAiA Programmable Drum Set, dated 1975, which came as a kit that that buyer would have to assemble according to instruction.

Another early programmable prototype was the Roland CR-78, 1978, which had four memory slots for the programmed patterns. It was quickly replaced by the Boss DR-55, also by Roland, which was the first drum machine to be fully programmable. However, it was engineer Roger Linn, who constructed and marketed the LM1, who made the real breakthroughs in electronic drum machines.

His company, Linn Electronics, sold his drum machine in 1979. Drum machines can be programmed in two ways, real time or step time, depending on how precisely the user wants to specify the moment the drum sounds. One can also create fills, breaks, rhythmic changes, and longer phrases simply by linking together bars which have been programmed differently.

The majority of drum machines can also be controlled by MIDI, which then allows one to program the machine via a computer or other MIDI device. By 2000, music workstations with integrated sequencing and drum sounds, and such hardware devices as general purpose samplers with either built-in or external sequencers, and software-based sequencing, and sampling, and the use of loops, had largely replaced the outdated drum machines.

A drum kit is made up of three banks, multiplied by thirteen pads, which yields thirty-nine sounds per kit. Sources for sounds can be chosen at will and assigned to the pads. The parameters, as for example pitch and level, can be fine-tuned to compose original and unique drum kits. There are also a great number of resources for phrase variations, including intro, fill-in, and ending patterns.