Temperature is how we measure how hot stuff is. According to a book I was reading recently,

The Farenheit scale was introduced in 1720 A.D.
The Centigrade or Celcius scale was introduced in 1742 A.D.
and the Kelvin scale (with Absolute Zero at the bottom) was introduced in 1854 A.D.

Though apparently there is some 'evidence' of an understanding of temperature comparison as early as 2000 B.C.