Arthritis can be of different types. Rheumatoid arthritis is one of them.  It is an autoimmune disorder. Autoimmune diseases are disorders, in which the immune system attacks its own body tissues. According to American Autoimmune Related Diseases Association, the term autoimmune disease covers 80 chronic illnesses. And rheumatoid arthritis is one of them. 

In case of rheumatoid arthritis, the immune system attacks synovial membrane and various tissues of the body. However, the prime target is synovial membrane. Thus there is inflammation of this membrane which secrets joint lubricant called as synovial fluid. This leads to joint problems and inflammation around the affected area.

However, the causes of this autoimmunity are still not clear. Some researchers believe that the cause may be genetic and some believe that the reason for autoimmune trigger might be bacterial, fungal or viral attack. Even though the causes are still not known, it is clear that autoimmunity plays a pivot role in rheumatoid arthritis progression.

In this autoimmune rheumatoid arthritis, there is formation of cysts in some parts of the body. Nodules are also common under the skin because there is inflammation of blood vessels. There is inflammation of joints and extreme pain followed by morning stiffness. In the long run the patients may also have cardiovascular problems, joint deformity etc.