Traditional music trackers cut time into "ticks" based on the system clock of the hardware the software is running on. For every tick, one event can take place. This event could be a sample playing, a volume changing, an effect taking place or a sample ceasing to play. This allows the musician to visually organize time in a gridwork of cells in which to set these events into motion, and thus decide the overall tempo of the music. This "time signature" can be altered programmatically throughout the piece of music, allowing tempo to rise, shift, swerve erratically or any combination of these as the musician sees fit.
