Tracker is the generic term for a class of software music sequencers which, in
their purest form, allow the user to arrange sound samples stepwise on a
timeline across several monophonic channels. A tracker's interface is primarily
numeric; notes are entered via the alphanumeric keys of the computer keyboard,
while parameters, effects and so forth are entered in hexadecimal. A complete
song consists of several small multi-channel patterns chained together via a
master list.

Tracker music lives on today. It can be found in modern computer games such as
the Unreal series and Deus Ex, as well as a considerable number of indie games.
However, the easy availability of software samplers/synthesizers and sequencers
has caused most professional musicians to adopt other music software.
Nonetheless, tracker software continues to develop (as of 2007). Some of the
early Amiga trackers such as ProTracker, OctaMED have received various updates,
mostly for porting to other platforms. ProTracker having resumed development in
2004, with plans for releasing version 5 to Windows and AmigaOS, but only
version 4.0 beta 2 for AmigaOS have been released. Other cross-platform trackers
include Renoise, MilkyTracker, and Skale.