In geometry, a position or position vector, also known as location vector or radius vector, is an Euclidean vector that represents the position of a point P in space in relation to an arbitrary reference origin O. Usually denoted x, r, or s, it corresponds to the straight line distance from O to P: : The term “position vector” is used mostly in the fields of differential geometry, mechanics and occasionally in vector calculus. Frequently this is used in two-dimensional or three-dimensional space, but can be easily generalized to Euclidean spaces in any number of dimensions.