A Drum Machine is an electronic instrument designed to replicate the percussive sounds made by drums. Drum machines can either use digital or analog technology to replicate drum sounds and more modern ones may allow percussion sounds to be sampled from external sound sources.
Although most drum machines are designed so that rhythms can be programmed in and them played back, some feature pads that allow them to be played be hitting with a stick or the hands similar to a traditional drum.
Although most prevalent in modern Electronica and dance music, a few rock bands have been known to use a drum machine in place of a live drummer. The British rock band, The Sisters of Mercy famously used a drum machine (referred to on album credits as Doktor Avalanche).
The early Roland TR303 was one of the first mass-produced drum machines. The TR808 and TR909 drum machines manufactured by Roland in the 1980s are perhaps the best known drum machines and defined the classic sound for many electronic artists. Since manufacture ceased these now change hands between musicians for many times the original selling price.