Temperature is a physical property of a system that underlies the common notions of hot and cold; something that is hotter generally has the greater temperature.
http://en.wikipedia.org/wiki/Temperature

Convert temperatures to and from celsius, fahrenheit, and kelvin. ... I have a downloadable temperature conversion program available. It converts between all temperature scales ...
http://www.onlineconversion.com/temperature.htm

Temperature measurement using modern scientific thermometers and temperature scales goes back at least as far as the early 18th century, when Gabriel Fahrenheit adapted a ...
http://en.wikipedia.org/wiki/Temperature_measurement

A good general discussion of the physics and concept of "temperature."
http://eo.ucar.edu/skymath/tmp2.html

A short introduction to temperature - including Celsius, Fahrenheit, Kelvin and Rankine definitions - online temperature converter
http://www.engineeringtoolbox.com/temperature-d_291.html