Types of Physical Quantities

Physical quantities split into exactly two categories:

• Fundamental (or base) quantities -- quantities that cannot be expressed in terms of any other physical quantity; they are the independent building blocks. In mechanics, electricity, thermodynamics, and so on, there are exactly seven of them: length, mass, time, electric current, temperature, luminous intensity and amount of substance.
• Derived quantities -- quantities that ARE built out of the fundamental ones by multiplication/division, e.g. area (length $\times$ length), volume, velocity (length/time), acceleration, force, and so on. …