Recipes for fudge tell you to heat a sugar syrup to two hundred and thirty degrees Fahrenheit. Taffy recipes give similar instructions, but with a temperature of two hundred and sixty-five degrees. And to make hard candy, you heat the mixture to three hundred degrees. The difference between fudge, taffy, and hard candy is in the amount of water each one contains: the less water, the harder the candy. The temperature of the syrup is what tells you how much of the syrup is water and how much is sugar. At sea level, pure water boils at two hundred and twelve degrees and never gets any hotter. But the boiling point for sugar is much higher than it is for water. And the temperature of the syrup, is a rough average of the temperatures of the two ingredients. Up to two hundred and twelve degrees, the temperatures of the two ingredients may be the same. But above that, only the sugar can get hotter.