The pretzel's shape is steeped in religious history. It is believed to have been invented by an Italian monk in 610 AD as a reward for children who learned their prayers. The dough was twisted to resemble arms crossed over the chest in prayer. The three holes in the pretzel are said to represent the Holy Trinity. In the Middle Ages, pretzels were an everyday food during Lent because they were made from a simple mixture of flour, water, and salt, containing no 'forbidden' ingredients like eggs or dairy. The dark, shiny crust is created by dipping the dough in a lye solution (sodium hydroxide) before baking, which triggers a rapid Maillard reaction.