Trigger

Trigger may mean:
 Trigger (firearms), a mechanism that actuates the firing of firearms
 Trigger pad, a device used in electronic percussion
 USS Trigger (SS-237), a submarine
 USS Trigger (SS-564), a submarine
 Trigger (horse), owned by cowboy star Roy Rogers.
 Trigger (guitar), the Martin N-20 guitar played by Willie Nelson.
 Trigger (Only Fools and Horses), a fictional character from the BBC sit-com Only Fools and Horses

In psychology and ethology:
An event which starts other events, or incites a response. See also releaser.

In computing:
 Trigger function in event-driven programming
 Database trigger, procedural code that is automatically executed in response to certain events on a particular table in a database
 Trigger circuit, IBM's name for a flip-flop.

In physics:
 Trigger (particle physics), hardware or software based device for the (online-)selection of specific event classes from large datasets (see also: ATLAS trigger system)

In music:
 Trigger (EP), an EP by the Swedish band In Flames
 "Trigger", a bonus song by The Rasmus from their 2005 album Hide from the Sun