Scleroderma is an autoimmune disease characterized by fibrosis of the skin and internal organs. It can be localized, affecting only the skin, or systemic, also involving internal organs like the lungs, kidneys, and gastrointestinal tract. The cause is unknown but involves genetic susceptibility and environmental triggers, and it results from immune system activation, inflammation, vascular damage, and overproduction of collagen by fibroblasts in the skin and organs.