At a potluck, you ate the best chocolate chip cookie—golden-brown, thick and chewy. Unfortunately, you don't know who made the cookie to get the recipe from, so you decide to recreate it. Using forward design principles, you might randomly choose a recipe from dozens of options, bake and observe the resulting cookies. If they are too thin, you might start over with a new recipe, add more flour or chill the dough longer and make a new batch. An alternative method is to start from the cookie characteristics you want and ask: What recipe and baking settings will produce that type of cookie? This method is called inverse design.