An ounce (oz) is a unit of mass in the imperial and US customary systems. It is defined as 28.3495 grams.
The ounce has roots in ancient Rome, where it was known as the "uncia." The term evolved through Latin and Old French into its current form. By the 14th century, the troy ounce was established for precious metals, weighing **31.1035 grams **. The avoirdupois ounce, commonly used today, was standardized in 1959.
Ounces are primarily used for measuring weight in cooking and food packaging. They are also used in the pharmaceutical industry and in various engineering applications. The ounce is prevalent in the United States and countries utilizing the imperial system.