* Celsius (°C): The most widely used scale globally, especially for scientific purposes and in most of the world's countries.
* Fahrenheit (°F): Used mainly in the United States.
* Kelvin (K): An absolute temperature scale (meaning it starts at absolute zero, the theoretical lowest possible temperature) and used primarily in scientific contexts.
Other less common scales:
* Réaumur (°Ré): Historically used in some parts of Europe.
* Rankine (°R): An absolute scale based on Fahrenheit degrees.
When referring to a thermometer, it's important to specify which scale you're using. If you don't, it's usually assumed to be Celsius, but always double-check to avoid confusion!
