A trigger is an experience that provokes or generates a memory or experience in someone.
While many use this word in the sense of triggering trauma, there are many other kinds of triggers, such as sexual triggers, happiness triggers, humiliation triggers and more.
Triggers can be quite diverse, appearing in the form of individual people, places, noises, images, smells, tastes, emotions, animals, films, scenes within films, dates of the year, tones of voice, body positions, bodily sensations, weather conditions, time factors, or combinations thereof.
Triggers can be subtle and difficult to anticipate, and can sometimes exacerbate post-traumatic stress disorder, a condition in which sufferers cannot control the recurrence of emotional or physical symptoms, or of repressed memory.
A trigger can can manifest in a variety of forms from exhibiting a changed mental state or physical reactions. A person that is experiencing a trigger may not even know this is happening.
Unless it is negotiated, willfully pushing a trigger of any kind on someone without permission is most often a consent violation.
In some publications a "trigger warning" may appear at the beginning of certain articles. These are to warn that the articles contain disturbing themes that may trigger traumatic memories for sufferers. An example of a trigger warning is: "TRIGGER WARNING: This content deals with an account of sexual assault and may be triggering to some people."