Regions
A region is a block on the timeline. It holds MIDI notes, audio, or automation. Double-click it to open the editor for what is inside.
A region is one block on the timeline. It holds one kind of material: MIDI notes, audio, or the automation for a single parameter. Other programs call this a clip.
Double-click a MIDI region to open the MIDI editor. Double-click an audio region to open the audio editor. Double-click an automation region to edit that curve. Click the timeline background to close the editor. Drag a region to move it in time. The cut tool splits one block into two.
The track is the lane. The region is an item on it. An instrument track holds MIDI regions. An audio track holds audio regions. An automation lane holds one parameter. Double-click empty space on an instrument track and you get a new MIDI region. Drop a sample on the timeline and you get an audio track with that sample already in a region.