Physical quantities are properties of matter and energy that can be measured. They help us understand the world around us by providing numerical values for things like length, mass, time, and temperature. For example, when we measure the length of a ruler, we are determining a physical quantity that tells us how long it is in units like centimeters or inches. These quantities can be classified into two main types: scalar and vector. Scalar quantities, like temperature and mass, have only magnitude, while vector quantities, such as velocity and force, have both magnitude and direction. Understanding these distinctions is essential in fields like physics and engineering.