This Ableton Live walkthrough breaks down what automation actually does: it sets a parameter to a specific value at a specific point in time, whether that's riding a track's volume or sweeping a filter's cutoff. In Session View, that automation lives inside clips rather than as a separate lane, which is worth knowing if you're used to Arrangement View workflows.
There are two core ways to create it. Draw automation directly with the pencil tool or grab a shape from the right-click menu for quick curves and ramps, or record it live by twisting a parameter with a Push, MIDI controller, or just your mouse or trackpad while playback runs.
The video demonstrates this on a Delay device, showing how a parameter that's been automated gets marked with a red dot, giving you a fast visual check on which knobs already have movement baked in.