A baker is a tradesperson who bakes and sometimes sells breads and other products made of flour by using an oven or other concentrated heat source. The place where a baker works is called a bakery. History Ancient history Since grains have been a staple food for millennia, the activity of baking is a very old one. Control of yeast, however, is relatively recent. By the fifth and sixth centuries BCE, the ancient Greeks used enclosed ovens heated by wood fires; communities usually baked bread in a large communal oven. Greeks baked dozens and possibly hundreds of types of bread; Athenaeus described seventy-two varieties. In ancient Rome several centuries later, the first mass production of breads occurred, and "the baking profession can be said to have started at that time." Ancient Roman bakers used honey and oil in their products, creating pastries rather than breads. In ancient Rome, bakers (Latin, pistor) were sometimes slaves, who were (like other slave-artisans) sometimes manumitted. Large households in Rome normally had their own bakers. During those times, most of the people used to bake their own bread but bakeries (pistrina) were popular all over the town. The Gauls are credited with discovering that the addition of beer froth to bread dough made well-leavened bread, marking the use of controlled yeast for bread dough. Medieval Europe In Medieval Europe, baking ovens were often separated from other buildings (and sometimes located outside city walls) to mitigate the risk of fire. Because bread was an important staple food, bakers' production factors (such as bolting yields, ingredients, and loaf sizes) were heavily regulated. For example, Henry III of England promulgated the Assize of Bread and Ale in 1267, subjecting all commercial bakers and brewers to various fees in order to practice their trade and imposing various regulations, such as inspection and verification of weights and measures, quality control, and price controls. Soon after the enactment of the Assize, "baking became a very stable industry, and was executed much more professionally than brewing, resulting in towns and villages having fewer bakers than brewers." Because ovens were expensive capital investments and required careful operation, specialized bakeries opened. Bakers were often part of the guild system, which was well-established by the sixteenth century: master bakers instructed apprentices and were assisted by journeymen. In Amsterdam in 1694, for example, the cake-bakers, pie-bakers, and rusk-bakers separated from an earlier Bread Bakers Guild and