### Theory:

Mass is the quantity of matter contained in a body.

Mass is a basic property of matter. The mass of each substance is in solid, liquid or gaseous state.
The following are the key points to know about mass:

1. All the matter contains mass, that is why it is known as the base quantity.

2. Mass is scalar quantity, that is mass only has numerical value.

3. The mass of an object is a constant value and it does not vary by the changes of gravity, place, temperature or pressure.

4. The SI unit of mass is kilogram.

In the International System of Units, the basic unit of mass is the kilogram (kg).

$$1$$ kilogram $$= 1000$$ gram
$$1$$ gram $$= 1000$$ mg
$$1$$ ton $$= 1000$$  kg

In our daily life, we did not use the word mass.