Here’s a quick rundown of the basic components that you’ll find in pretty much every bearing:

The Outer Race or outer ring determines the outside diameter and width of the bearing.
An Inner Race or inner ring that fits inside the outer ring and is much smaller in size. This gives us the bore size of the bearing.
Rolling Elements like Balls or Rollers in between the two rings are the key components that allow the bearing to spin freely.
A Cage in between the two rings keeps the balls and rollers in place and prevents them from falling out.
A Dust shield or Seal keeps dust and other contaminants out, which can grind down and wear out the interior components of the bearing much faster.
Lubricants such as grease and oil minimize the friction between the bearing’s internal components. Lubricants create a thin film around the surface of the bearing internals that prevents, or at least reduces, metal to metal contact thus reducing friction, heat and wear. Lubricants also help keep contaminants and moisture out, and prevent corrosion of the bearing components.
Identifying Bearing Part Numbers
Bearings from different manufacturers use a common part numbering scheme so you can easily find the correct replacement parts using just the part numbers. Bearing part numbers also tell you exactly what type of bearing you have, its size and many other specifications.