Motion Paths
When a layer’s Position has keyframes, the path between them appears in the viewport as a spatial curve: this is the motion path. Drag a point on the path to move that keyframe in space, or drag a handle to shape the curve between keyframes.
Alt-drag a motion path point to quickly convert it into an Eased keyframe and manipulate its Bezier handles directly. Whenever you want to manipulate those handles later you must hold Alt while dragging or clicking the handle.
Alt+Cmd-drag a handle to break its pairing so the incoming and outgoing curves can be shaped independently.
Easing ticks along the motion path show the position of the animated shape between two keyframes. Dragging the orange/yellow ticks lets you manipulate the easing curve on the motion path itself — which automatically updates the easing in the Graph Editor and Timeline, and vice versa.
Alt-drag an easing tick to decouple easing on either side of a keyframe. Alt-drag it again to re-couple the two sides so the easing matches.