Final answer:
The two most common forms of arthritis are osteoarthritis and rheumatoid arthritis, both of which cause joint pain and stiffness but have different underlying causes and affected areas.
Step-by-step explanation:
The two most common forms of arthritis are osteoarthritis and rheumatoid arthritis. Osteoarthritis is often associated with aging and wear and tear of the articular cartilage, with symptoms like joint pain and stiffness that may worsen following exercise. Meanwhile, rheumatoid arthritis is an autoimmune disease characterized by inflammation of the joint capsule and synovial membrane, leading to severe damage to the articular cartilage and potential joint deformity, particularly affecting hands, feet, and cervical spine. Treatments for these conditions focus on alleviating pain and improving joint function through lifestyle changes, medications, and possibly surgery.