Arthritis is a common condition that causes pain, stiffness, and swelling in the joints. It can affect people of all ages, but it is most common in older adults. There are many different types of arthritis, but the most common type is osteoarthritis.
Osteoarthritis is caused by the breakdown of the cartilage that cushions the ends of bones. This can happen due to age, injury, or obesity. Rheumatoid arthritis is another common type of arthritis that is caused by the immune system attacking the joints.