Here's a breakdown:

* Independent: They cannot be expressed in terms of other quantities. For example, you can't define length using mass or time.

* Sufficient: You can use fundamental quantities to derive all other quantities. For example, you can define speed as distance (length) divided by time.

Why do we need fundamental quantities?

* Consistency: Defining a system of units based on fundamental quantities ensures consistency and avoids circular definitions.

* Simplicity: It simplifies the measurement and understanding of other physical quantities.

* Universality: Fundamental quantities have universal applicability across different fields of science and engineering.

Examples of Fundamental Quantities:

* Length: A measure of distance.

* Mass: A measure of the amount of matter in an object.

* Time: A measure of duration.

* Electric Current: A measure of the flow of electric charge.

* Temperature: A measure of the average kinetic energy of particles in a system.

* Amount of Substance: A measure of the number of elementary entities in a system.

* Luminous Intensity: A measure of the power emitted by a light source.

Important Note: The specific choice of fundamental quantities can vary depending on the scientific context. For example, in some fields, force or energy may be considered fundamental quantities instead of mass.