Disaccharides are sugars which are formed when two monosaccharides(simple sugars) are joined by glycosidic linkage with the aid of a condensation reaction which involves the elimination of a water molecule from the functional groups.
Disaccharides are also known as double sugar due to the combination of two sugar molecules through glycosidic linkage. Similar to monosaccharides, they are also soluble in water. Sucrose, lactose, and maltose are few examples of a disaccharide.