A unit vector is often denoted by a lowercase letter with a circumflex, or "hat": (pronounced "i-hat"). The term directionvector is used to describe a unit vector being used torepresent spatial direction, and such quantities are commonly denoted as d.

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It is used to represent spatial direction. A unit vector in a normed vector space is a vector (often a spatial vector) of length 1. A unit vector is often denoted by a lowercase letter with a circumflex, or "hat". The term direction vector is used to describe a unit vector being used to represent spatial direction, and such quantities are commonly denoted as d.

A Unit Vector is simply a Vector with a magnitude (length) of 1 unit. You can calculate the magnitude of a vector by summing the squares of each of the components, then taking the square root.