For most quantities a unit is necessary to communicate values of that physical quantity. For example, conveying to someone a particular length without using some sort of unit is impossible, because a length cannot be described without a reference used to make sense of the value given.

What is a unit and why is it important?

Chemists measure the properties of matter and express these measurements as quantities. A quantity is an amount of something and consists of a number and a unit. The number indicates how many (or how much), and the unit describes the scale of measurement.

Why are units important in our everyday life?

Measurement provides a standard for every day things and processes. From weight, temperature, length even time is a measurement and it does play a very important role in our lives. The money or currency we use is also a measurement.