When we animate characters, there are two main ways of animating them. One is to get the meshes of each pose and animate by morphing between the different meshes. I think this is how quake2 did it. Another method is hierarchical bones. This is the normal way it is done now, and the hierarchy's transforms are used to affect a mesh via some skinning data (which verts to affect and by how much).
Animating that hierarchy is usually called playing an animation. If you play two anims at the same time and interpolate between them, it's called tweening.
We use morphing tech now for facial control because it allows more fine control without the costs when the number of verts per bone gets really low.