Keyframe

A frame that stores a full image, or a moment where a value is fixed and the rest is filled in. The craft is what happens between them.

The keyframe is a saved certainty in a stream of inference: video codecs store a full image only occasionally, describing every other frame as differences; animation stores fixed values and interpolates the between. In both, the keyframe is where the work says, here, exactly this.

What happens between them is the craft in both senses: in animation, the easing between keys is where motion acquires character, mechanical or alive. In delivery, keyframe spacing decides where a viewer can land when seeking and how gracefully a stream recovers. Sparse keys save weight; generous keys save patience.