Units of measurement

A unit of measurement is a definite magnitude of a physical quantity, defined and adopted by convention or by law, that is used as a standard for measurement of the same physical quantity. Any other value of the physical quantity can be expressed as a simple multiple of the unit of measurement.

For example, length is a physical quantity. The metre is a unit of length that represents a definite predetermined length. When we say 10 metres (or 10 m), we actually mean 10 times the definite predetermined length called "metre".

The definition, agreement, and practical use of units of measurement have played a crucial role in human endeavour from early ages up to this day. Different systems of units used to be very common. Now there is a global standard, the International System of Units (SI), the modern form of the metric system.

In trade, weights and measures is often a subject of governmental regulation, to ensure fairness and transparency. The International Bureau of Weights and Measures (BIPM) is tasked with ensuring worldwide uniformity of measurements and their traceability to the International System of Units (SI).

Biblical and Talmudic units of measurement

Biblical and Talmudic units of measurement were used primarily by ancient Israelites and appear frequently within the Hebrew Bible as well as in later Judaic scripture, such as the Mishnah and Talmud. These units of measurement are still an important part of Jewish life today. There is much debate within Judaism, as well as by outside scholars, about the exact relationship between measurements in the system and those in other measurement systems, such as the English units system used in the United States of America. Classical statements, such as that an Etzba was seven barleycorns laid side by side, or that a Log was equal to six medium-sized eggs, are so indefinite and vague as to be nearly useless. Nevertheless, the entire system of measurement corresponds almost exactly with the Babylonian system, and in all probability the Israelite measurement system was derived from the Babylonian, with some lesser level of influence from the Egyptian system. It may therefore be assumed that the relationship between the Israelite measurements and contemporary units is the same as the relationship between the Babylonian system and contemporary units.