Rheumatoid Factor (RF) is an autoantibody test that detects antibodies directed against the body's own immunoglobulin G (IgG). This test is commonly used to help diagnose rheumatoid arthritis and other autoimmune conditions. While rheumatoid factor is present in approximately 70-85% of patients with rheumatoid arthritis, it can also be found in other rheumatic diseases, chronic inflammatory conditions, and even in some healthy individuals, especially with increasing age. The presence of rheumatoid factor, particularly in high titers, is associated with more severe disease and increased risk of systemic complications in rheumatoid arthritis. However, a negative test does not rule out rheumatoid arthritis, and a positive test alone is not diagnostic. This test is most valuable when used in combination with clinical symptoms, physical examination, and other laboratory tests to establish a comprehensive diagnosis and assess disease prognosis.