Skeletal animation is a technique in computer animation in which a character consists of 2D/3D model and hierarchical set of interconnected bones used to animate the mesh.
Skeletal Animation (sometimes referred as Bone Animation) is a system of animating a 2D or 3D model by overlaying the the model itself (also referred as Mesh) with a bone and joint control mechanism referred as the rig or skeleton.
In 2D models, the image used for the model is broken down to individual segments, and the pivot points connecting them create the rig for the model. In 3D models the rig may be more complex.
There are many software products which support skeletal animation, and it is used extensively in the game industry as it allows the player to animate a character in real-time. In unity3d skeletal animation is controlled via the animation tab by adding keyframes and curves.
