When heating up a substance (in our case a liquid) the heat causes the molecules into the substance to increase their thermal agitation. This in turn causes a raise of the temperature of the substance. In water (because its molecules are polar) there are hydrogen bonds between molecules. These bonds do not let much place for the molecules to oscillate very much when water is heated up. It means more heat needs to be added to water to cause the same increase in temperature as compared to other substances. Also this leads to a very high specific heat of water as compared to other common substances.
Water has the highest specific heat. The specific heat of water is 1 calorie per gram degree centigrade. It is because of a result of hydrogen bonding between its molecule and a high heat of vaporization. The specific heat of any substance other than water is less than 1. The specific heat of a material is generally determined by heating a sample of the material to a certain temperature and then putting it in a quantity of water whose temperature is also known. We carefully note the maximum temperature rise of the water. Since the heat gained by the water is equivalent to the heat lost by the sample of material. We can calculate the specific heat of latter.