Nonlinear Animation
Where do keyframes live? In the Timeline? The Graph Editor? The Dope Sheet? Sure, these three editors can access keyframes for editing, but are the keyframes really there? Perhaps the real keyframes are in the slider of an animated property whenever it turns yellow, or maybe they live behind Blender’s user interface and scatter like roaches every time you minimize the window. Maybe there’s a keyframe behind you right now.
The truth is these are all silly answers, but Where do keyframes live? is a serious question with a real answer. Keyframes live in F-Curves, which are the same thing as animation channels. Animation channels live in actions, and actions – the ones that directly affect the animation, at least – live in the Nonlinear Animation editor.
Also known as the NLA, the Nonlinear Animation editor is the executive headquarters of every animation in Blender. With this editor, whole actions can be sped up, slowed down, combined...