### Osteoarthritis (OA) OA is the most common form of arthritis. It occurs when the cartilage that cushions the ends of bones in your joints gradually deteriorates. This can cause pain, swelling, and reduced motion in the joints. It often affects the knees, hips, hands, and spine. ### Rheumatoid Arthritis (RA) RA is an autoimmune disease where the immune system attacks the joints, causing inflammation. This can lead to severe joint damage if not treated. Common symptoms include joint pain, swelling, and stiffness, especially in the mornings or after periods of inactivity. ### Psoriatic Arthritis This type of arthritis affects some people who have psoriasis, a condition that features red patches of skin topped with silvery scales. Joint pain, stiffness, and swelling are the main symptoms, and they can affect any part of your body, including your fingertips and spine. ### Gout Gout occurs when urate crystals accumulate in your joint, causing inflammation and intense pain. It often affects the big toe but can occur in any joint. Symptoms include sudden, severe attacks of pain, swelling, redness, and tenderness in the joints. ### Lupus Lupus is an autoimmune disease that can affect your joints and many organs in your body. Symptoms vary widely but can include joint pain, fatigue, and a butterfly-shaped rash on the face. It is more common in women, particularly those of African-American descent.