Automation in music is a valuable tool. A modern DAW project might feature dozens (or even hundreds) of parts. There’s no way you can keep on top of them all with a single pair of hands and eyes. By automating parameters, you can add sophisticated details to your projects that will be perfectly reproduced each time you play it back.
The simplest kind of automation is probably a volume fade. By automating the volume of a part in your DAW, you can make a new part emerge from nothing, or create a fade out at the end of a track. But automation in music goes much deeper than this.
Most modern DAWs (such as Logic Pro, Pro Tools, and Ableton Live) let you automate parameters right across a project, from synths and effects to global parameters. You can use automation to create filter sweeps, give complex movement to a synth part, switch on and off effects, or even change the tempo of your song halfway through.
