A music tracker (sometimes referred to as just tracker for short) is a type of music sequencer software for creating music. The music is represented as discrete musical notes positioned in several channels at discrete chronological positions on a vertical timeline.A music tracker's user interface is usually number based. Notes, parameter changes, effects and other commands are entered with the keyboard into a grid of fixed time slots as codes consisting of letters, numbers and hexadecimal digits.Separate patterns have independent timelines; a complete song consists of a master list of repeated patterns.