It doesn't "start at 0"; there are both negative and positive temperatures on the Centigrade scale.
The Absolute scale (degrees Kelvin) which starts at absolute 0. The Centigrade scale that starts at the freezing point of ice. The Fahrenheit scale that starts at the freezing point of brine.
Centigrade degrees or the "Celsius" scale.
Centigrade
On the Celsius, or Centigrade temperature scale, freezing is 0 (zero) degrees. On the Celsius, or Centigrade temperature scale, freezing is 0 (zero) degrees.
32 degrees Fahrenheit- the temperature at which water freezes.
Centigrade or Celsius Temperature Scale
0 degree centigrate
0 degrees C
273
It is based on units of ten, and the boiling point of water on the centigrade scale is 100 degrees. That's what centigrade means: Centi=100. Gradus=step or degree.
Celsius and Centigrade
That is the Celsius scale. We used to call it Centigrade.