When the pressure of the atmosphere is 1013 mbar (this is about the average pressure for a place which is at sea level), water will boil (turn into steam) at 100 degrees Celsius. This is the boiling point. Boiling happens in a boiler. 100 degrees Celsius is the same temperature as 212 degrees Fahrenheit, 80 degrees Réaumur and 373.15 Kelvin.