Systemic sclerosis is an autoimmune connective tissue disease that affects the skin, blood vessels, and internal organs. There are two major subtypes: limited, characterized by skin changes limited to the hands, face, and CREST syndrome features; and diffuse, with generalized skin thickening. Systemic sclerosis causes fibrosis of skin and internal organs due to vascular dysfunction, immune dysregulation, and excessive collagen deposition. It commonly involves the lungs, gastrointestinal tract, kidneys, heart, and musculoskeletal system. Prognosis depends on the degree of internal organ involvement.