This chapter describes rheumatology in the question and answer format. Rheumatoid factor is an autoantibody (IgM, IgG and IgA) directed against the Fc (fragment crystalization) fragment of human immunoglobulin. This chapter covers the initial clinical characterization of arthritis, rheumatoid arthritis, systemic lupus erythematosus (SLE), spondyloarthropathies (spondyloarthritides) (SpAs), vasculitis, osteoarthritis, systemic sclerosis (scleroderma), Sjögren’s syndrome, crystal arthropathies, miscellaneous, osteoporosis, antiphospholipid antibody (APLA) syndrome (Huges syndrome), and inflammatory muscle diseases. Antinuclear antibodies (ANA) are directed against one or more components of the cell nucleus. The component of the nucleus includes DNA, RNA, proteins as well as complexes of proteins with nucleic acid. Antineutrophil cytoplasmic antibodies (ANCAs) are heterogeneous group of IgG autoantibodies directed against certain proteins (mainly enzymes) in the cytoplasmic granules of neutrophils and lysosomes of monocytes. Rheumatoid arthritis (RA) is the most common form of chronic inflammatory arthritis with multisystem involvement that affects approximately 1% of the adult population throughout the world.