Rheumatoid arthritis is an autoimmune disease that causes inflammation, swelling, and pain in the joints and organs. It is caused by both genetic and environmental factors like smoking and obesity. Symptoms include joint pain, stiffness, swelling, fatigue, skin lumps or redness, and hand deformities. It is diagnosed through physical exams, blood tests, and x-rays. Treatment involves physical and occupational therapy, lifestyle changes, and medications like DMARDs, NSAIDs, and steroids to manage symptoms and prevent complications such as osteoporosis, infections, and heart or lung problems.