: It is a long-term condition that alternates between periods of increased disease activity ( flares ) and periods of relative calm ( remission ). Key Symptoms

is a chronic, systemic autoimmune disease characterized by persistent inflammation of the joint lining, or synovium. Unlike osteoarthritis, which is caused by mechanical "wear and tear," RA occurs when the body's immune system mistakenly attacks its own healthy tissues. Core Characteristics

: The immune system sends antibodies to the joint linings, causing inflammation that can lead to permanent damage of cartilage, bone, and surrounding tissues.