When firing in ceramics we use these things called cones to determine what is going on in the kiln. Cones are made from a ceramic material that melts a certain amount when exposed to heat over a period of time. The cone bends to a certain degree depending on how much heat it has been exposed to, the angle of the cone tells gives you a cone reading. You use different cones depending on what temperature you would like to fire to and measure.
Different kinds of ceramics are fired to different temperatures. The temperature you fire to depends of the kind of clay your use, the firing method (type of kiln) and finished effect you desire. We use two main categories to describe firing temperatures: earthenware and stoneware. Earthenware means firing below 970 °C and stoneware above 1200 °C. The following chart tells you what cones represent what temperatures.