[windwaves]

can someone explain to me what these are and what they are for ? 

Thank you.

[mgalusha]

Firing a gun
Causing an action in a database
Turning on your home theater amp remotely
Roy Rogers horse...

Seriously, what kind of trigger are you referring to? I'm guessing you mean in regards to stereo/home theater gear. Most triggers operate by sending a 12V signal to the amp or whatever device is to be triggered, causing it to turn on. This can also be used to lower projector screens, dim lights, and other simple tasks.

[PeteG]

I'll go for the Horse.