A means of generating a control signal based on how much pressure is applied to the keys of a MIDI keyboard. Most instruments that support this do not have independent pressure sensing for all keys, but rather detect the overall pressure by means of a sensing strip running beneath the keys. Aftertouch may be used to control such functions as vibrato depth, filter brightness, loudness and so on....
AKS
This is one of the classic pieces in analogue synth history. Brian Eno still caries one
around and Klaus Schule Schulze still uses his on every recording. The pin-block
patching is a little strange at first, but the versatility is like that of a modular unit. You
can patch anything into anything and the built-in reverb, while a little cheezy, can be
anywhere in the signal chain.