In chemistry, a solution is a homogeneous mixture of two or more substances. The substances that are dissolved are called solutes. The substance the solutes are dissolved in is called the solvent. An example from everyday experience is a solid like salt or sugar (which are crystalline solids), dissolved in a liquid (like water). Gases can dissolve in liquids. An example is carbon dioxide or oxygen in water. Liquids may dissolve in other liquids and gases in other gases.