A cake is a form of food, usually sweet, often baked. Cakes normally combine some kind of wheat byproduct, a sweetening agent (commonly sugar), a binding agent (generally egg, though gluten or starch are often used by vegetarians and vegans), fats (usually butter or margarine, although a fruit puree can be substituted to avoid using fat), a liquid (milk, water or fruit juice), flavours and some form of leavening agent (such as yeast or baking powder). Cake is often the dessert of choice for meals at ceremonial occasions, particularly weddings or birthday parties.