The physical sciences are called exact sciences. The exactness comes from measurements. The study of all subjects in science and technology involves measurements of various types. Measurements are important both from theoretical and practical point of vies. It is only through measurements that were can verify the existing laws and theories, and postulate new laws and theories. Even in our daily life, measurement plays an important role. Were buy and sell things by measuring their size ,volume and mass- were buy milk by volume, vegetables and fruits by mass (or weight ) etc. more expensive goods/ materials such as a gold, diamond etc. , should be weight accurately.
To know if the airs were breathed and the water was drink are safe to use, concentrations of the pollutants should be measured up to parts for million (ppm) levels. Measurement of time has a very important role to play in our day-to –day life as well for the industry. In events such as sports, even the time duration as small as 0.01 second may affect the final outcome. In rocketry, time duration as small as a microsecond may be very crucial. All machine and their components must meet high standard of measurement control. What would you do, if the bulb you bring from the market does not fit into the bulb holder into your table lamp?
All machines are assembled from hundreds of components. Such components are manufactured at many different places. Even when one of the components differ in size, it will not be possible to assemble the machine. All components must have the required dimensions. This will require accurate measurements. It is these obvious that were need to measure in one way or the other in all spheres of life.
All measurements are made by making a comparison with a standard of the same kind. Each accepted standard of measurements is called a unit. The modern system of units came as a result of gradual improvements in the ancient way of measurement.