Basic, fundamental, or standard, whatever you may call it when speaking for measurement units, you will land at the same seven units. Whether Physics, Chemistry, or Mathematics, the seven fundamental units of measurement play a crucial role in the subjects. As the name suggests, these are the units for measuring different kinds of physical and non-physical quantities. They get described as a definite magnitude of a quantity. These units are defined and adopted by the convention and are used as a standard for the measurement of the same kind of quantities.