The primary causes of arthritis can be broadly categorized as follows: 1. Age and Wear and Tear: Osteoarthritis, the most prevalent form of arthritis, is primarily caused by the natural aging process and wear and tear on the joints over time. The cartilage that cushions the joints gradually deteriorates, leading to joint pain and stiffness. 2. Autoimmune Dysfunction: Rheumatoid arthritis (RA) is an autoimmune disease in which the body's immune system mistakenly attacks its own tissues, including the joints. The exact cause of RA is unknown, but it is thought to involve a combination of genetic and environmental factors.