Hydrated salts are compounds that contain water molecules within their crystal structure. These water molecules are chemically bonded to the salt, which can affect the salt's properties, such as its color, solubility, and stability. Common examples of hydrated salts include copper(II) sulfate pentahydrate and calcium sulfate dihydrate. When hydrated salts are heated, they can lose their water content in a process called dehydration, resulting in an anhydrous salt. This change can be reversible; when water is added back, the anhydrous salt can rehydrate and regain its original form. Hydrated salts are often used in various applications, including chemical reactions and desiccants.