Measurement helps us make sense of the world around us
Measurement is the quantitative way of comparing of one thing with another. The International System of Units, also known as the SI, is by far the most widely used system of measurement in the world. It is a coherent system of seven base units (kilogram, metre, second, ampere, kelvin, mole, candela) which allow science, industry and trade to measure all physical objects and phenomena in the same way, using the same units and get the same number.
Originally measurement units were defined by physical objects or properties of materials. An example of this is the metre, which was originally defined by a metal bar exactly one metre in length.
However, these physical representations can change over time or as a result of environmental changes, and are therefore no longer accurate enough for today's research and technological applications.