the gram

The gram or gramme, symbol g, is a unit of mass, and is defined in the SI system of units as one one-thousandth of a kilogram (i.e., 1 × 10−3 kg). One ounce avoirdupois is 28.34952 grams (see Conversion of units of mass).

Although the gram is not an SI base unit, it is a submultiple of the kilogram, which is a base unit. In SI, gram is also the root to which SI prefixes are applied. However, the gram is a base unit of the older cgs system of measurement, a system which is no longer widely used. The gram is an essential measurement unit in scientific endeavors worldwide.

A gram was originally defined as the weight of one cubic centimeter of water at its densest. This occurs at a temperature near four degrees Celsius. However, its definition was changed to the mass of a metal artifact in the eighteenth century.