Since the development of measuring processes, a number of systems of unit have been put forward. Here are a few:

• F P S System (Foot–Pound–Second)
  In this system of unit, length is measured in foot; mass in pound; and time in second. This is also known as British system of measurement.
• C G S system (Centimeter–Gram–Second)
  In this system of unit, length is measured in centimeter; mass in gram; and time in second.
• M K S system (Meter–Kilogram–Second) or Metric system
  Here, length is measured in meter; mass in kilogram; and time in second.
• SI Units
  The representations or prototypes of units are maintained in many international centres worldwide, like the International Bureau of Weights and Measures at Sevres near Paris, National Institute of Standard Technology or National Physical Laboratory in the USA or Bureau of Indian Standards in New Delhi, India. Internationally everyone strictly follows a standard system of units. This system is called the S.I. units (Standard International). Calibrations used for measurement have to be standardized so that they remain constant, under normal everyday life. If this was not done, then there would be chaos in the world as everyone's measurement would be different!! In SI there are seven fundamental units and two supplementary units.

MKS units and the SI system of units are nearly similar and now-a-days used in most measurements.