The unit of measurement refers to a specific quantity defined and adopted by agreement, which is used to quantitatively express the size of the same quantity.

All kinds of physical quantities have their own units of measurement, and the number of selected substances displayed under specified conditions is the standard of basic units of measurement. The choice of basic quantity can be different in different periods and disciplines. For example, in physics, seven physical units, such as time, length, mass, temperature, current intensity, luminous intensity and quantity of matter, are taken as basic quantities, and their unit names are seconds, meters, kilograms, kelvin, amperes, Candeira and moles.

Unit of measurement: such as pounds, millimeters, centimeters, inches, etc.