Some physical quantities are completely described by a numerical value alone. Such quantities are called **scalars** or **scalar quantity**.

But for description of some physical quantities value as well as direction is required. Velocity of a particle is one such example. The magnitude of velocity is represented by a number such as 5 m/s and tells us how fast a body is moving. But description of velocity is complete only when direction of velocity is specified. Such quantities are called **vectors**.

## Equality Of VectorsEdit

Two vectors are equal if and only if they have same magnitude(numerical value) and direction. **Thus, a parallel translation of a vector does not bring about any change in it.**

## Addition Of VectorsEdit

Vectors cannot be added subtracted by normal laws of algebra. they are added according to **The triangle law of vector addition.** The parallelogram law of vector addition and The polygon law of vector addition are extensions of triangle law.