Retriggering is a tracker technique in which a sample

Sampling (music)

In music, sampling is the act of taking a portion, or sample, of one sound recording and reusing it as an instrument or a different sound recording of a song or piece. Sampling was originally developed by experimental musicians working with musique concrète and electroacoustic music, who physically...

 is replayed a set number of times within a certain timeframe.

Basic theory of tracker time

Traditional music trackers cut time into "ticks" based on the system clock of the hardware

Hardware

Hardware is a general term for equipment such as keys, locks, hinges, latches, handles, wire, chains, plumbing supplies, tools, utensils, cutlery and machine parts. Household hardware is typically sold in hardware stores....

 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

Time signature

The time signature is a notational convention used in Western musical notation to specify how many beats are in each measure and which note value constitutes one beat....

" 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.

The retrigger effect

For tracker musicians working at very slow speeds, the need to escape the confines of this time-grid is often apparent. For instance a musician might want to add a drum roll, but lack the time resolution to do so effectively. The retrigger effect allows this by calling an event that tells the software to replay the triggered sample at a set rate within the timeframe of the tick on which the event transpires. This ability to circumvent this one rigid limitation of the typical music tracker software has become a staple of the tracker scene, in some cases inspiring artist names and album titles based on the concept of retriggering.