Defined according to wikipedia: 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. Specifically, temperature is a property of matter.

The Kelvin is the base unit of temperature in SI. Other common temperature units are: degree Celsius, degree Fahrenheit, degree Rankine, degree Delisle, degree Newton, degree Réaumur, degree Rømer.

Units in converter are (some additional info included):

• Kelvin - the SI base unit. Defined by two points:
  • 0 K is absolute zero - the lowest possible temperature. No heat energy remains in a substance, so nothing could be colder. It is equal to -273.15°C and -459.67°F
  • 273.16 K is triple point of water (precisely: Vienna Standard Mean Ocean Water) - which is equal to 0.01°C and 32.018°F
• degree Celsius (°C) - named after Anders Celsius (1701 – 1744).
  The 0°C on the Celsius scale was defined as the freezing point of water and 100°C was defined as the boiling point of water under a pressure of one standard atmosphere. This definition was valid from 1744 and is still really close to current definition.
  Currently "degree Celsius" is defined as:
  • −273.15 °C is absolute zero - the lowest possible temperature.
  • 0.01 °C is triple point of water - precisely: Vienna Standard Mean Ocean Water.
This was redefined in 1954 by international agreement - and makes the Celsius unit intervals equal to Kelvin intervals.
• degree Fahrenheit (°F) - freezing point of water is 32 °F and the boiling point 212 °F.
• degree Rankine (°R, °Ra) - 0 °R is absolute zero, however Rankine degree is defined as equal to one degree Fahrenheit. This means, that intervals for Fahrenheit and Rankine is the same, only "zero point" is different.
• degree Delisle (°De)
• degree Newton (°N)
• degree Réaumur (°Ré)
• degree Rømer (°Rø)