Disaccharides are a type of carbohydrate that are made up of two sugar units (two monosaccharides). The elements that make up all carbohydrates are carbon, hydrogen and oxygen. Common disaccharides are sucrose, maltose and lactose. For example, sucrose (table sugar) is made up of glucose and fructose which are both monosaccharides. Lactose, which is sugar in milk, is made up of galactose and glucose. The structure and physical properties of disaccharides depends on the monosaccharide units it is made up of.
Sucrose: glucose + fructose