Temperature

Temperature is how hot or cold something is. The human body can feel the difference between something which is hot and something which is cold. To measure temperature more accurately, a thermometer is used. Thermometers use a temperature scale to record how hot or cold something is. The scale used in most of the world is in degrees Celsius, sometimes called "centigrade". In the US and some other countries degrees Fahrenheit are more often used while scientists mostly use kelvins to measure temperature because it never goes below zero.

Scientifically, temperature is a physical quantity which describes how quickly molecules are moving inside a material. In solids and liquids the molecules are vibrating around a fixed point in the substance, but in gases they are in free flight and bouncing off each other as they travel. In a gas the temperature, pressure and volume of the gas are closely related by a law of physics.