The basic concept of ball and roller bearings and the variety of available configuration details are described. The explanations of the fundamental engineering technology of rolling element bearings include (1) the mechanics of rolling-contact component stresses and deformations from applied bearing loads and element inertia with motion kinematics, (2) modern computer software now readily available to analyze rolling element bearings, (3) lubricant supply techniques, (4) component materials and preparation, and (5) life, reliability, and failure modes.