Arthritis literally means "joint inflammation". The word comes from the Greek words arthro meaning "joint" and -itis meaning "inflammation". Arthritis can occur in any joint in the body, from the small joints of the fingers to the major joints, such as the hips or knees. The two main types of arthritis are degenerative, meaning it is caused by excessive use of the joint, or autoimmune, meaning the immune system attacks the joints, believing them to be disease-causing cells. There are other types, including some caused by an infection of the joint or by the body depositing different substances in the joint, which can cause inflammation. The inflammation, regardless of its cause, can lead to swelling, pain and stiffness. This pain and stiffness can cause movement loss and limit the normal day to day activities of an arthritis patient. However, with treatment, the pain and stiffness can be managed and most daily activities can be accomplished.

Degenerative arthritis types are caused by excessive use of the joint. This means it is more often seen in the elderly than other age groups. However, people who use a joint a lot, such as sports players or factory workers that perform repetitive movements all day may also develop any of the degenerative arthritis types. The degeneration is caused when the tissues surrounding the joint become worn and unable to work properly. The degeneration can be treated with glucocorticoid injections and the pain can be managed with over the counter pain medicines such as acetaminophen or ibuprofen.

Autoimmune arthritis types occur when a person's immune system attacks their joints. The most common types of autoimmune arthritis are rheumatoid arthritis and psoriatic arthritis. The treatment for these diseases is similar; both rely heavily on controlling the inflammation and preventing joint damage. This can be accomplished using either non-steroidal anti-inflammatory drugs (NSAIDs) or disease modifying antirheumatic drugs (DMARDs). DMARDs are thought to improve rheumatoid arthritis by interrupting the cycle of inflammation and joint damage. Once the inflammation is under control, many people find that their pain decreases to a manageable level. This is done with over the counter pain medications.

Some arthritis, such as septic arthritis, is caused by a joint infection. This is usually treated with antibiotics to get rid of the infection and mild painkillers to manage the pain until the infection and resulting inflammation, has cleared up. Patients usually recover fully from septic arthritis, although many may develop a form of degenerative arthritis later in life. Another type of arthritis is caused by deposits of certain molecules in the joints. This is either gout or calcium pyrophosphate dihydrate deposition disease, CPPD. Gout is caused by deposits of uric acid crystals in the joint. With CPPD, the body deposits calcium pyrophosphate crystals in the joint. Treatment is usually aimed at preventing any more crystal formation and controlling symptoms of deposited crystals. For a single joint this is accomplished by draining the fluid off the joint and injecting corticosteroid, while taking NSAIDs to control the pain. When multiple joints are affected, corticosteroid injection is impractical so an oral course of corticosteroidal treatment is followed. Gout can also be controlled through dietary changes.