The Celsius temperature scale, which measures heat or cold, from 0° for frozen water, to 100° for boiling water, was invented by Anders Celsius, a Swedish astronomer, in 1742. He named the scale the centigrade scale, and people may occasionally still see temperatures listed with this term. In 1954, however, scientists officially named the temperature scale after the astronomer to honor his work.
The original scale differs from the modern use of Celsius. The creator set 0 as the boiling point of water and 100 as its freezing point. This was reversed shortly after his death to the more modern usage.
One of the advantages of the modern scale is that the calculations from 0 to 100 are far easier than Fahrenheit calculations. 0°C is equivalent to 32°F. The boiling point of water, under 1° of atmospheric pressure, is 100°C or 212°F. The base 100 method is simply easier to calculate than the more complex Fahrenheit formula. Converting Celsius to Fahrenheit follows this basic formula: F = (C x 1.8) + 32.
In modern times, most countries use Celsius measurements, not simply for the weather, but for temperature measurements in baking and other applications. Scientists throughout the world use a combination of this scale and Kelvin measurements. The Kelvin scale is based on the fixed points of absolute zero, where nothing could be colder, and all matter solidifies, and the triple point of water, where gas, liquid and solid water are equally used. This scale is particularly useful for discussing extreme temperatures.
In the US, people typically use Fahrenheit in daily use, but most weather channels also give the conversion to Celsius. Cookbooks made in the US usually give conversions as well, since baking would be completely thrown off by following the instructions for one temperature scale in an oven that uses the other. A cake baked for an hour at 325°C (625°F) would be a disaster.