Inflammation of a joint or a state characterized by inflammation of joints.

Arthritis is caused by inflammation, of the tissue lining the joints. Some signs of inflammation include redness, heat, pain, and swelling. In some types of arthritis, the joints involved can become severely damaged. There are different types of arthritis. In some diseases in which arthritis occurs, other organs, such as the eyes, the chest, or the skin, can also be affected.