What points are accepted as basic on the Celsius scale?

Most countries use a temperature scale called the Celsius scale. It was proposed by the Swedish physicist Anders Celsius (1701-1744). On this scale, zero is taken to be the melting temperature of pure ice at normal atmospheric pressure (101,325 Pa), The boiling point of distilled (purified from impurities) water at normal atmospheric pressure is assigned a value of 100, The scale is divided into 100 equal parts, called degrees.