The Celsius temperature scale is used by scientists and meteorologists and has been adopted by some countries across the world. Scientists and meteorologists find this temperature scale to be more convenient than the Fahrenheit temperature scale because the freezing point and boiling point of water on the Celsius scale is 0 °C and 100 °C (which are figures that one can relate to) while on the Fahrenheit scale it is 32°F and 212°F respectively. Many countries throughout Europe, Asia, and South America use the Celsius temperature scale because it is used in most scientific fields of study and weather forecasting.
Fahrenheit is the temperature scale for everyday use in the United States. It is used mostly in weather reports in the USA, so it has some advantages over the Celsius temperature scale in the USA. In the USA, Fahrenheit is more familiar to people than Celsius, so more Americans can understand what a temperature means when it is given as degrees Fahrenheit.
The Kelvin scale is a thermodynamic temperature scale, meaning it measures the average kinetic energy of a molecule in a substance. The more kinetic energy a molecule has, the more heat the molecule possesses.
The Kelvin scale is an absolute temperature scale to measure the degrees of hotness and coldness. It was developed by the Scottish physicist William Thompson, who is largely known by his honorific, 1st Baron Kelvin. The Kelvin scale starts at 0K which is equivalent to -273.15°C or -459.67°F.