100 degrees Celsius is an important temperature because it is the boiling point of water at sea level. This means that at this temperature, water changes from a liquid to a gas. This is a critical point in the water cycle, as it is the point at which water evaporates from the Earth's surface and returns to the atmosphere.

100 degrees Celsius is also important in cooking. It is the temperature at which most bacteria are killed, making it a safe temperature to cook food. This is why many recipes call for food to be cooked at or above 100 degrees Celsius.

Finally, 100 degrees Celsius is also used as a reference point for other temperature scales. For example, the Fahrenheit scale is based on the freezing point of water (32 degrees Fahrenheit) and the boiling point of water (212 degrees Fahrenheit).