<human>:  Where does the water in a glass of water come from?
<bot>: The water in a glass of water comes from the atmosphere. The water in the atmosphere is made up of two parts: water vapor and water droplets. Water vapor is a gas that is made up of water molecules. Water droplets are tiny water particles that are suspended in the air. The water vapor and water droplets in the atmosphere are constantly being replenished by rain and other sources.