Temperature is a thermodynamic property of objects. It is an “indirect measurement of the kinetic energy of the particles that make up matter” (Lerner 2008). Temperature determines the direction of energy flow between two objects. When brought into contact with each other, the faster molecules in the higher temperature object will collide and increase the speed of movement of the slower molecules in the lower temperature object. This process stops when the two objects have the same average molecular kinetic energies, or in other words, they are in thermal equilibrium with each other. Temperature is one of the most commonly measured parameters. The thermometer is a device with an established temperature scale, based on its property of expansion at different temperatures. When the thermometer is in thermal equilibrium with other objects, it indicates the temperature degrees of the objects. Temperature is measured relative to four temperature scales: the Fahrenheit (F), Celsius (C), Kelvin (K), and Rankine (R) temperature scales, whose names are based on the names of the original scientists temperature scales. The Fahrenheit scale, designated by the letter F, is a non-metric temperature scale, developed in the early 18th century by a German physicist, Daniel Gabriel Fahrenheit (1686-1736). On this scale, the normal freezing point (or ice point) of water is at 32 oF, and the normal boiling point (or vapor point) of water is at 212 oF. Fahrenheit originally chose 0°F for the coldest temperature he could obtain in his laboratory (by mixing ice and salt water) and 96°F, a "practical number with many subdivision factors” for human body temperature (Tipler 565). The Celsius scale, designated by the letter C, is a metric scale of temperature, developed in 1742 by an astr...... middle of paper ......temp is a negative scale: new record reached with a high-energy ultracold gas." Science News February 9, 2013: 10. Science in Context Web November 25, 2013. Lerner, Ed. K. Lee and Brenda Wilmoth Lerner. "The Gale Encyclopedia of Science Detroit: Gale, 2008. The science in context. November 24, 2013. Singh, Onkar. “Zero law and thermodynamics”. . Science in Context Web. November 25, 2013. Thompson, Ambler and Barry N. Taylor B.8 Factors for Alphabetically Arranged Units in the Guide to the International System of Units (.SI). , 2008. Tipler, Paul Allen and Gene Mosca. “Temperature Theory and Kinetics of Gases.” New York: WH Freeman, 2008. 565. Print..