In audio-recording parlance, automation refers to the ability of a recording system (traditionally a mixing console, more recently a DAW) to record, and subsequently reproduce, real-time adjustments to parameters such as track volume. In DAW systems, automation extends to cover real-time parameters of plug-ins (e.g. synthesizers and signal processors). To make this work, both DAW and plugin must support bi-directional communication of parameter values, i.e.,

• Plugin to host: user manipulates GUI controls, changes are recorded by a host DAW.
• Host to plugin: DAW recreates user's manipulations automatically using playback.

More to come…