A physical quantity is a property of an object or phenomenon that can be measured and expressed numerically. Examples include length, mass, time, and temperature. These quantities can be described using units, such as meters for length or kilograms for mass, allowing for clear communication and comparison. Physical quantities can be classified into two main categories: scalar and vector. Scalars have only magnitude, like temperature, while vectors have both magnitude and direction, such as velocity. Understanding physical quantities is essential in fields like physics, engineering, and everyday life, as they help us quantify and analyze the world around us.