Shape Keys (2.62)

Shape keys are used to create fine tuned changes in the mesh without adding geometry. This is great for doing animations, and for performance in the game engine because extra geometry slows down the responsiveness of the character. Some examples of where shape keys can be useful are animating a rig, changing facial expressions on a character, and lip synching with audio. The appearance of a mesh deformation can be simulated, without using modifiers. You should not use shape keys unless the geometry is final because adding geometry will mess up the shape keys. Shape keys affect the mesh data block, not the object itself. The appearance of an object can change at the object level, for example when an object is scaled or rotated, or even moved, if you are in perspective mode. This is not the same as a shape key change because the location, scaling, and rotation information are not stored in the mesh data. To animate these, use the Loc, Rot, and Scale channels. Shape keys are animated using the Shape Keys editor in the Dopesheet.