Newb question: aftertouch?

[Sifunkle]

Hello, hopefully I'm not polluting the wrong forum with inappropriate questions...

Just trying to program some patches on some softsynth VSTs, and I'm bothered by something that has always stumped me: what the heck is aftertouch? I know I've looked it up a few times, but I'm still pretty clueless so it must not have penetrated my skull.

I've never managed to find out what it does in any way. This may be because I'm not actually playing a keyboard where I'd use a particular control that it affects or some such. I notice it all over the place though: on the oscillators and noise generators and everything.

Anyway want to use nice simple words and gimme a breakdown? Cheers in advance

 

[Brenton]

Aftertouch is just pressure sensitivity. For example, if you strike the note but don't fully release it, a keyboard that has aftertouch will modulate the tone according to the release of the note, as would a grand piano.

 

[DD83]

Some sounds actually can change drastically with the use of aftertouch. You pres a key, while still pressing the key you apply more pressure to the key and the sound will modulate or change depending on the sound and what you may have programmed/assigned the aftertouch to do.