This article assumes you’re somewhat familiar with ND-spaces (where N can be replaced by some arbitrary number). The two ND-spaces we’ll talk about are 2D-space and 3D-space.
When you’re dealing with 3D graphics, the most common concepts you’ll come across are points and vectors. They’re used pretty much everywhere. But what are they, and what differences are there between the two?
As you might know, both points and vectors are represented by their coordinates, such as (X, Y) in 2D-space or (X, Y, Z) in 3D-space. They do look very similar, but they are distinct concepts.
A point represents a point in ND-space. It practically has no area, so it’s infinitesimal.
A vector represents a direction and a length in ND-space. How can it represent a direction? Doesn’t that require two points in ND-space? Yes it does. One of the two points is implicit, whereas the other, the one you specify yourself, is explicit. The implicit point is at the point that represents the origin in that ND-space. In 2D-space the origin is (0.0, 0.0) and in 3D-space the origin is (0.0, 0.0, 0.0). If you specify a vector in 3D-space as (1.0, 2.0, 3.0), that means you’re specifying a vector that starts at the point (0.0, 0.0, 0.0) in 3D-space and is directed towards the point (1.0, 2.0, 3.0) in 3D-space.