a ray is a line that has a begining point, but no end point
a ray is 1 dimentional, it only goes one direction, left and right
a plane is 2 dimentional and extends indefinitely
it goes left and right and up and down
think of it like this
you have a piece of paper with no height
you draw a line starting at a point on the paper and it goes infinitely in the other direction
the paper is a plane, the line on it that has a starting point is the ray
