 So let's do an example of this. Let's imagine that we had some ice, and we can plot the temperature of the ice against time. And we start up with ice, I don't know, say minus 20 degrees centigrade, and we put a fire under it. So what happens is the temperature will rise until it gets to zero degrees centigrade. At that point, even though there's still a fire underneath it, the temperature will not rise, instead it will steadily turn from 100% ice to 100% water. And that will take a while. So we begin with the most ice, a little bit of water that's melted, and as time goes on more and more water melts. So eventually by here all the ice is turned to water, and then the temperature will start rising again. And it will rise until we get to 100 degrees. At that point, the temperature will stop rising. So now what's going to happen is here you're going to start off with 100% water and not 100% steam, and as it goes along here more and more of the water will turn into steam, until eventually it will be 100% steam and then the temperature can keep on rising as you make the steam hotter and hotter. And this is what happens to any substance, not just water. The energy here, it's the latent heat of fusion. The energy needed to turn something from solid to a liquid is actually quite large. It's 334 kilojoules, that's 334,000 joules per kilogram. But then you appear the latent heat of vaporization to turn a liquid into a gas is even more immense. It's actually 2,265 kilojoules, 2,265,000 joules per kilogram. So these are very large numbers indeed.