If a Track is the member of a band or orchestra, then a pattern is a page of sheet music that each member is reading. Each track can play up to 16 unique patterns, and patterns may be chained if needed. A pattern itself is made up of a maximum of 16 steps. When a pattern plays (press the play button to start or stop playing), each track steps through these steps
By default most tracks step through their patterns at a speed of 16 step (e.g. 4 beats, or one bar) per pattern. The overall speed is determined by the "BPM" setting in the Song settings. However it is possible to modify this speed (see "b.div"/"BPM div" parameter on the "Pttn" page) on a per-pattern basis. Note that, by default, the Chord track is the only exception; the default settings cause the pattern to be stepped through at a slower pace (there "b.div"/"BPM div" is set to divisor of 4 instead of 1, so that a a pattern now takes 4x as long to be stepped through, compared to the other tracks.
It is also possible to change the length of a pattern to something smaller than 16 steps (see "Pt.Ln"/"Ptrn Len" parameter) on a per-pattern basis. Changing the length of a pattern can create complex and interesting sounding polymeters, and can even allow for different time signatures within one song.
Pattern playback can further be influenced by mute/unmute cycling (MU.Ln/UM.Ln/M.U.OF); this can make a a track's playback cut in and out rhythmically. Song mode fragments can further influence how a pattern is played back by applying re-triggering effects and automation.
Given the vast amount of ways patterns and their constituent steps can be modified and transformed, it is possible (and common) to create full, complex sounding songs with just one pattern per track.