Rolling element bearing, also known as a rolling bearing or simply bearing is a part of rotating machinery that carries a load by placing rolling elements (such as balls or rollers) between two bearing rings. Bearing performs three functions – Support the shaft, Carry the load from the shaft, and reduce friction. The importance of rolling-element bearing is such that it is often called the heart of machinery. Refer to the below picture to understand the components of a bearing. The size or shape of components may vary in different types of bearings but all bearings will have similar components as shown in the picture. 
Types of Rolling Element Bearings
Bearings are categorized based on the shape of the rolling element which can be either Ball or a Roller. Further, both Ball and Roller bearings may be of Radial type or thrust type. Please see the picture below to understand the type of bearings.
Deep Groove Ball Bearings– These are the most used bearings throughout the world. Common applications such as small electric motors, gearboxes, household appliances, hand tools, agriculture machinery, pumps, fans, two-wheelers, three-wheelers etc have these bearings. Because of their internal design, they can take radial load and light axial load. Designation of these bearings starts with “6”. For example, 6200, 609, 627, 6210, 6311, and 6110 are the Deep groove ball bearings. 
Angular Contact Ball Bearings– Angular contact ball bearing has an internal design in such a way that they can take heavy axial loads as well as radial loads. Actually, they have curvature on the inner and outer ring raceway which supports the rolling element when the heavy axial load comes on a shaft. Major applications are machine tools such as Lathe machines, heavy motors, and generators, car wheels. Industrial pumps, Gearboxes, Renewable energy, Compressors, Trucks, trailers, and buses. The designation of these bearings starts with “7”. For example, 7206, 7312, 7322, etc. are angular contact ball bearings. 
Self-Aligning Ball Bearings – As the name of bearings, these are capable of taking larger misalignments than any of the other bearings. They can take radial as well as light axial loads. These bearings are generally used in Pulp & Paper, Fans, and Material handling. Designation of these bearings starts with “1” such as 1203, 1211, 1226, etc are Self-Aligning Ball Bearings
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Angular Contact Thrust Ball Bearings- These bearings can take heavy radial as well as heavy axial loads, although originally designed to support the rotary tables of drilling rigs and other machine tools. 
Cylindrical Roller– These bearings are suitable for heavy radial loads and to take axial expansion o the shaft, these are the separable bearings means the inner ring and outer ring of these bearings can be separated during the assembly process. Typical applications of these bearings are Stationary gearboxes, Automotive gearboxes, Electric motors, Wind turbines, Off-highway equipment, Pumps and compressors, Material handling equipment, Textile machinery, Railway vehicles, and Rolling mills. Designation of these bearings starts with NU, for example, NU 210, and NU 320 are cylindrical roller bearings. There are different other variants of these bearings where designation starts with NJ, NUP, N, etc. 
Needle Roller Bearing – These bearings are similar in design to cylindrical roller bearings but their rollers are small in diameter compared to length, due to this they have small cross-sections and are suitable for application with very little radial space. Needle roller bearings come in many variants as per application requirements. A typical application of this bearing is the connecting rod of an internal combustion engine. 
Tapered Roller Bearing- Tapered roller bearing can take heavy radial as well as heavy axial load. Tapered roller bearings feature a cup and cone assembly. The cup is comprised of the outer ring and the cone assembly consists of an inner ring, rollers, and cage. As the outer ring is separable and conical in shape so by adjusting one single-row tapered roller bearing against a second tapered roller bearing on a shaft and applying a preload, a rigid bearing application can be achieved. Some of the applications of Taper roller bearings are gearboxes, hoisting equipment, rolling mills, machines in the mining industry, and truck wheels. The designation of these bearings starts with “3” such as 33209, 30211, etc are taper roller bearings. 
Spherical Roller Bearing– Spherical roller bearings are used when there are very heavy radial and axial loads in applications prone to misalignment or shaft deflections that can be a real challenge. Some of the applications of these bearings are Renewable energy, Mining, mineral processing and cement, Material handling, Pulp & Paper, Industrial transmission, and Marine. Designation of these bearings starts with “2” for example 22326, 23220, etc. are spherical roller bearings. 
CARB Toroidal Roller Bearing– CARB bearings have rollers of special shape which make them a combination of cylindrical and spherical roller bearings. So, these bearings are an excellent choice when a self-aligning roller bearing with axial floating capability is required. Some of the applications are Industrial transmission, Metals, Pulp and Paper, Mining, mineral processing and cement, Industrial fan, and Marine. These bearings can replace Spherical roller bearings also. The designation of CARB bearing starts with “C” for example C6006, C2207, and C3076 are CARB Toroidal bearings. CARB bearings are manufactured by only SKF, which is its trademark name
Cylindrical Roller Thrust Bearing– Cylindrical roller thrust bearings are designed to accommodate heavy axial loads and impact loads. They must not be subjected to any radial load. The bearings are very stiff and require little axial space. Some of the applications are Material Handling, Industrial transmissions, and Machine tools. 
Needle Roller Thrust Bearing– needle roller thrust bearings are fitted with a form-stable cage to reliably retain and guide a large number of needle rollers. Needle roller thrust bearings provide a high degree of stiffness within a minimum axial space. In applications where the faces of adjacent machine components can serve as raceways, needle roller thrust bearings take up no more space than a conventional thrust washer. Typical applications are Machine tools, Cars and light trucks, Trucks, trailers and buses, Two and three-wheelers. 
Taper Roller Thrust Bearing– tapered roller thrust bearings are designed to accommodate heavy axial loads and peak loads. The bearings are very stiff and require little axial space. 
Spherical Roller Thrust Bearing– spherical roller thrust bearings have specially designed raceways and asymmetrical rollers The bearings can accommodate axial loads acting in one direction and simultaneously acting radial loads The load is transmitted between the raceways via the rollers at an angle to the bearing axis, while the flange guides the rollers. Some of the applications of spherical roller thrust bearings are Industrial transmission, Metals industry, Pulp and paper, Industrial fans, Marine, Mining, mineral processing, and cement industry.