Steam, physics, chemistry and engineering, refers to vaporized water. At temperatures around 100 degrees Celsius at atmospheric pressure and the standard vapor, pure, transparent and liquid is gaseous water is 1600 times the volume. Steam is hotter than the boiling point of water naturally. Superheated steam at higher temperatures usually called steam. Which is in contact with water vapor evaporates. at any temperature reduction that takes the form of water vapor again.