Measurement is the process of comparing homogeneous quantities. To measure a physical quantity, we compare it with another homogeneous one. This homogeneous quantity is called the unit of measurement. For example, to measure the length of an object, we compare it with a specific length which we consider as the unit of measurement. To measure a physical quantity, we use not only the unit of measurement but also a numerical value. For example, a desk has a length of 1.2 m. The 1.2 is the numerical value and the m is the unit of measurement. Fundamental physical quantities are those that arise directly from our intuition and are not defined with the help of other quantities. Such physical quantities are length, time, and mass. The units of measurement of fundamental quantities are defined and called fundamental units. The meter (m), the second (s), and the kilogram (kg) are fundamental units in Mechanics.