Autodesk Maya is a powerful tool to animate in 3D. However, in order to animate, one has to understand how to set up keys in order to make the shot work. Animschool offers one of the best online courses to teach Maya under the tutelage of professional animator Justin Barrett. This following clip is from one of his classes.
In this clip from his "Introduction to Maya" class, Animschool's instructor Justin Barrett explains the history and usage of keyframes in Maya animation setup.