About the celsius scale
Celsius is a temperature scale where 0 °C indicates the melting point of ice and 100 °C indicates the steam point of water.
The Celsius scale was developed by a Swedish scientist called Andreus Celsius.
The symbol for celsius is °C and just like fahrenheit, it's also measured in degrees.
The official unit of measurement is Celsius in every country except the United States
The temperature of "absolute zero" is at -273.15 °C which is a state where no energy remains in a substance. This by the way is precisely 0 Kelvin. It is very cold! Just think about how cold it is when it's -30C in the winter.
Some places on Earth measure -40 or even colder temperatures but where I live in Ontario, Canada, I would say cold starts when it's below -10C but we rarely get days below -20C thanks to Lake Ontario!