In science, there are two primary types of numerical quantities.
Scalars are numerical quantities that can be described with a single number.
However, when describing other quantities, it is often necessary to express both a magnitude and a direction. An effective way of expressing such quantities is through the language of vectors. A vector can be thought of as a collection of scalars in which each scalar corresponds to a numerical description of a different dimension of the given quantity. For example, temperature and mass are scalar quantities while position and velocity are vector quantities. While the purely mathematical concept of vectors can be applied to any number of dimensions, scientific quantities are normally limited to three.