Arthritis is an inflammation of the joints which can be caused by a wide variety of things. It is one of the leading causes of mobility issues for people over 50, and it is widespread across all cultures and classes. Arthritis is also ancient: evidence of arthritis has even been uncovered in dinosaurs, suggesting that this joint condition is natural, caused simply by wear and tear on the joints as someone (or some creature) ages.

The major feature of arthritis is pain, which can sometimes be severe. The condition may also be accompanied by swelling, tenderness, clubbing around the joint, and stiffness. Arthritis sufferers often have trouble moving joints affected by arthritis, making it hard for them to move or to use their hands. As many people who have been around the elderly have noted, arthritis often strikes the hands, because the joints in the hands are heavily used throughout one's life, and very old people sometimes have gnarled, clubbed fingers as a result of repeated bouts of arthritis.

One of the most common causes of arthritis is degeneration, which can be caused by disease or the natural aging process. Other causes include infection and trauma, especially repeated trauma, and some people develop arthritis due to metabolic changes. Arthritis can also flare up in concert with another disease; for example, gout is often linked with arthritis, because the uric acid crystals associated with gout can end up in any joint, not just the big toe.

Some common forms of arthritis include: osteoarthritis, caused by degenerative disease; inflammatory arthritis, caused by inflammation around the joint; septic arthritis, caused by bacterial infection either at the joint or somewhere else in the body; juvenile arthritis, which appears in children and young adults; and rheumatoid arthritis, caused by immune system attacks to the lining of the joints.

There is no cure for arthritis, but steps can be taken to treat the symptoms and the underlying problems which may cause it. Various exercises can be used to gently stretch and strengthen the joints, as recommended by a physical therapist, and some medications may be used to bring down the inflammation and treat the pain associated with arthritis. If the arthritis is being caused by an underlying health problem, treatment for that condition may help to resolve the arthritis; many people also use medicated soaks, massage, and other complementary treatments to deal with their arthritis.