Before canvas.
In physics, Forces are an example of a quantities that have a definite size (magnitude) and a definite direction.
For example, you might have a force of 20 newtons to the left.
Quantities like this as known as vectors and can be represented by using an arrow. The length of the arrow corresponds to the magnitude of the quantity and the direction the arrow points corresponds to the direction of the quantity.
Vectors are quantities that need a magnitude and a direction to fully describe them.
Distance is a quantity. Displacement is a quantity.