Osteoarthritis is a type of joint disease that results from the breakdown of cartilage and underlying bone. It commonly affects the hands, feet, spine, and large weight-bearing joints like the hips and knees. The most common symptoms are joint pain, stiffness, and crackling noises. Risk factors include mechanical stress, excess weight, nerve impairment, and hereditary or hormonal conditions. It is diagnosed through x-rays, blood tests, and examination and shows features like bone spurs, cysts, and cartilage loss.