Convolution Reverb

Convolution is a mathematical process where two functions can be combined to produce a morphed version that has characteristics of both.
A convolution reverb is a signal processor that can be modeled to make an audio signal sound like it's in a specific acoustical space, for example, Carnegie Hall or the Taj Mahal.
Typically a very short duration sound is used to capture the characteristics of the room, like a balloon pop, an electrical spark, or more often a starter pistol. The reverberation created by the room from the impulse signal is input into the convolution processor via a microphone usually placed in the center of the room. The processor then strips out the original impulse signal and what's left is the reverberation decay envelope. This can then be used to recreate the sound of that space.
Another technique involves using a broadband sine wave sweep. This provides even more information, including the frequency response characteristics of the reverb.
Sound designers often will use convolution to create very specific reverbs. For example, in the Lord of the Rings trilogy, Peter Jackson's sound crew used the convolution reverb characteristics of a garbage can to create the sound inside an Orc helmet.

[PaolaMontielM]

Thank you man, this is very much easier to understand.

[FabioKasper]

Woow... Amazing, Mr. Audio. I've heard some convolution plugins can be a cpu drainer. Not sure if this was on the past though. Cheers!