Skeletal animation
Also said as Frame-by-frame animation, Bone animation, Cutout animation, Traditional animation
Two ways to make a character move. Frame by frame means a new drawing for each pose. Skeletal means one drawing (or model) attached to bones, with the computer moving the bones.
Frame by frame gives you total freedom, at the cost of redrawing everything for each new outfit or move. Skeletal gives you smooth motion at any speed, blending and reuse, but it can look like a paper puppet.
Say it
“Use skeletal animation for all enemies, because we need 40 of them and blending between moves. Do the player frame by frame, at 12 drawings a second, since that is what people will look at most.”
Where you’ve seen it
Every frame of Cuphead was drawn by hand and inked on paper. Rayman Origins took the other route, with Ubisoft's UbiArt Framework animating the hand-drawn art by puppeting it.
Not to be confused with rigging
Skeletal animation is the way of moving a character. Rigging is the job of building the bones and controls it needs.