An excerpt in the book "College Algebra by Michael Sullivan is that:
When the graph of a function is given, its domain may be viewed as the shadow created by the graph on the x- axis by vertical beams of light. Its range can be viewed as the shadow created by the graph on the y-axis by horizontal beams of light.
I did't get it and i also sought in google to get some idea but i can't find one. Can anyone help me to understand it maybe with some graphics.