1. Mass: The quantity of matter in an object.

2. Length: The distance between two points.

3. Time: The duration of an event.

4. Electric current: The flow of electric charge.

These quantities are the foundation of all other measurements. For example, velocity can be expressed as the rate of change of distance with respect to time, while acceleration is the rate of change of velocity with respect to time. In this sense, all other quantities can be derived from these four fundamental quantities.