Heat is energy and as such is measured in calories (or joules).
Temperature is measured by instruments such as thermometers and recorded in units such as Kelvin and degrees Celsius (or Fahrenheit). Heat capacity is the quantity of heat required to change the temperature of a substance. In comparison with other substances, water has a very high heat capacity. It can absorb or lose a large amount of heat before there is a change of
temperature. It takes 1 calorie (4,184 joules) of heat energy to raise the temperature of 1 gram of pure water by 1 degree Celsius, whereas the heat capacity of lead takes 0.03 calories (0,128 joules) and copper 0.09 calories (0,385 joules). When water changes state, far more heat energy is exchanged during the process. The heat properties of water (latent heat of fusion; latent heat of vaporisation and heat capacity) illustrate how phenomenal a substance water is, and the important role that these properties play in supporting life on Earth.