A baker's dozen, also known as a long dozen, is a unit of measurement equivalent to 13 items, rather than the standard 12. This conversion originated in medieval England, where bakers were required to include an extra item in every dozen to avoid penalties for shortchanging customers. The term 'baker's dozen' has since been adopted in various contexts, including science and everyday life, to represent a quantity that is one more than a standard dozen. In practical applications, a baker's dozen is often used in recipes and cooking, while in scientific contexts, it may be used to represent a margin of error or a safety factor.