Anhydrides are chemical compounds formed by the removal of water from an acid. They can be classified into two main types: acid anhydrides and basic anhydrides. Acid anhydrides are derived from acids and can react with water to form the corresponding acid, while basic anhydrides are formed from bases and can react with water to produce a base. These compounds are often used in various industrial applications, including the production of esters and amides. Anhydrides can also play a role in organic synthesis, where they serve as reactive intermediates in chemical reactions.