The SI preferred unit for temperature is the
kelvin but for everyday use the celsius scale is
most commonly used in the UK. Older texts may refer to the
'centigrade' scale. Although numerically
identical to the celsius scale, the term 'centigrade'
was abandoned in 1947. In the UK and some other countries
(most notably the USA) the Fahrenheit scale is still widely
used. The Reamur and Rankine scales are obsolete and
included here only for historical interest.