All pastries have the minimum of ingredients - flour, liquid (water or milk), salt and fat (usually butter, but can be shortening, lard or oil) - in different proportions by weight, being handled and baked in various ways. Additional ingredients are found in some recipes, such as eggs and sugar, contribute to leavening, flavor and browning. Except for croissant, Danish and brioche, which make use of yeast, most leavening agents for pastries are steam and air. They are decorated - braided, shaped, filled - in a myriad of ways.