Being an arrow, a Euclidean vector possesses a definite "initial point" and "terminal point". A vector with fixed initial and terminal point is called a bound vector. When only the magnitude and direction of the vector matter, then the particular initial point is of no importance, and the vector is called a free vector. Thus two arrows formula_1 and formula_3 in space represent the same free vector if they have the same magnitude and direction: that is, they are equipollent if the quadrilateral "ABB′A′" is a parallelogram. If the Euclidean space is equipped with a choice of origin, then a free vector is equivalent to the bound vector of the same magnitude and direction whose initial point is the origin.