Disaccharides are carbohydrates that are made up of two monosaccharide sugar units linked together. The process of joining two monosaccharides is called dehydration.
Examples of disaccharides:
Sucrose - table sugar
Maltose - a disaccharide produced when starch is broken down
Lactose - the sugar found in milk based products
This is an image of a sucrose disaccharide molecule:
