The origin of a
coordinate system is the point
where the axes of the system intersect. The most common systems are two-dimensional
(contained in a plane) and three-dimensional
(contained in a space) Euclidean systems,
having two and three perpendicular axes, respectively.
The origin divides each of these axes into two halves, a positive side and a
negative side. Points can then be located with reference to the origin by giving
their numerical coordinates -- that is, their positions along each axis either
in the positive or negative direction. The coordinates of the origin are always
all zero, for example (0,0) in two dimensions and (0,0,0) in three.