Carbohydrates are classified into three main categories based on the number of sugar units they contain:

• Monosaccharides: These are the simplest sugars, consisting of a single sugar unit. Examples include glucose, fructose, and galactose.
• Disaccharides: These are composed of two monosaccharides joined together by a glycosidic bond. Examples include sucrose (glucose + fructose), lactose (glucose + galactose), and maltose (glucose + glucose).
• Polysaccharides: These are complex carbohydrates made up of many monosaccharide units linked together. Examples include starch, glycogen, and cellulose.