A deep groove in a ball bearing refers to the specific design feature of the bearing's inner and outer raceways, which allows it to accommodate radial and axial loads while enabling smooth and efficient rotation. The deep groove is a critical aspect of the ball bearing's construction and contributes to its performance in various applications.

The primary function of a bearing is to enable the controlled transfer of loads and motion while minimizing friction and wear. Bearings achieve this through the use of rolling elements, such as balls or rollers, or through sliding surfaces, depending on the specific type of bearing. By doing so, bearings help to maintain the integrity and alignment of rotating shafts, axles, and other mechanical components, ensuring smooth and efficient operation of the machinery.