 The relationship between points p and q may involve a direction (for example, from p to q), so when it does, this relationship can itself be represented by a vector, given by

In a two- or three-dimensional space ("n" = 2, 3), this can be visually represented as an arrow from p to q.In any space it can be regarded as the position of q relative to p. It may also be called a displacement vector if p and q represent two positions of some moving point.The Euclidean distance between p and q is just the Euclidean length of this displacement vector