An egg's freshness makes a huge difference in its flavor and how it cooks. A really fresh egg will be cloudy with two distinct whites – one thick, one thin – and a yolk that sits up high on the thick white. As an egg ages, it loses flavor and turns clearer, and its whites get thinner. A fresh egg is great for poaching: It doesn't want to feather away in the water, and the thick white surrounds the yolk. But you don't want to hard-boil a new egg: The white sticks to the shell so much you'll hate peeling it. To check freshness without cracking an egg, put it in a glass of water. If it's fresh, it'll lie happily on its side. The more it wants to "stand up," the older it is. (If it floats, the only thing to do with it is throw it at an annoying neighbor's house.)