What is a vector?

What is a vector by Dr. Walter Lewin.

Vector, in physics, a quantity that has both magnitude and direction. It is typically represented by an arrow whose direction is the same as that of the quantity and whose length is proportional to the quantity’s magnitude.

Although a vector has magnitude and direction, it does not have position.

That is, as long as its length is not changed, a vector is not altered if it is displaced parallel to itself.

A vector is an object that has both a magnitude and a direction. Geometrically, we can picture a vector as a directed line segment, whose length is the magnitude of the vector and with an arrow indicating the direction. The direction of the vector is from its tail to its head.

Vector is a term that refers to quantities that cannot be expressed by a single number (a scalar), or to elements of some vector spaces. They have to be expressed by both magnitude and direction.