These are two ways of drawing animation. Straight-ahead action is where you draw each frame of an action one after another as you go along. With pose-to-pose, you draw the extremes – that is, the beginning and end drawings of action – then you go on to the middle frame, and start to fill in the frames in-between.

Pose-to-pose gives you more control over the action. You can see early on where your character is going to be at the beginning and end instead of hoping you’re getting the timing right. By doing the main poses first, it allows you to catch any major mistakes early. The problem with it is that sometimes it comes off as too neat and perfect.

Straight-ahead action is less planned, and therefore more fresh and surprising. The problem with it is that it’s like running blindfolded… you can’t figure out where you’re supposed to be at any one time.

Mastering both techniques and combining them is the best approach to being a successful animator because then you can get both structure and spontaneity.  And incidentally, this distinction is just as important in computer animation, where molding a pose at each keyframe is the equivalent of making a drawing.