In the 15th century, bakeries in Germany began to market one-layer cakes for customers' birthdays in addition to cakes for weddings. During the 17th century, the birthday cake took on its contemporary form. These elaborate 17th century cakes had many aspects of the contemporary birthday cake, like multiple layers, icing, and decorations. However, these cakes were only available to the very wealthy. Birthday cakes became accessible to the lower class as a result of the industrial revolution and the spread of more materials and goods.