Gram
Definition: A gram (symbol: g) is a metric unit of mass equal to one-thousandth of a kilogram (0.001 kg).
History/Origin: Introduced with the metric system in France in 1795, originally defined as the absolute weight of one cubic centimeter of pure water at 4°C.
Current Use: Used globally for small masses in cooking, packaging, laboratory work, and retail measurements.
Ounce
Definition: An ounce (symbol: oz) is a unit of mass equal to 1/16 of a pound or approximately 28.3495 grams.
History/Origin: Derived from the Roman 'uncia', meaning one-twelfth part, and standardized in the British Imperial system in the 19th century.
Current Use: Used in the United States and United Kingdom for measuring smaller weights like food portions, mail, and precious metals.