Skeletons provide an intuitive way to pose and animate your model. A well-constructed skeleton can be used for a wide variety of poses and actions, in much the same way as the all-purpose skeletons in our bodies can. On the other hand, a skeleton might also be used to provide less flexibility — to ensure that a model cannot move beyond certain restricted conditions. For example, look at your wrist: you can easily bend it straight up or down, but side-to-side motion is very limited.
Analogous to real skeletons, skeletons in Softimage are usually made up of bones that are linked by joints that can rotate. However, unlike real skeletons, the combination of bones and joints is referred to generically as a chain in Softimage.
