text: Graphically, a domain is how far across the x-axis a graph spans.  A range is how far up and down the y-axis a graph stretches.\n\nSome graphs, like y = x^2, are limited in range.  In this case, y can never be less than 0, so the range is y>=0.  x in this case can be anything, so the domain for x is all real numbers.  Graphically that makes sense - you can graph your parabola as far left and right that you want to, but not up and down.\n\nOther graphs, like y = sin x, are even more limited in the y direction.  Graphically, you can see that y can't go past -1 or 1, so the range is -1 <= y <= 1.\n\nAnd still others have no bounds.  y = x exists everywhere - there's no limit on what x or y can be.\n\nThis is probably a lead-in to graphing more advanced functions, such as y = (x^2 - 1)/(x + 1), where you'll have a domain of all real values except for x = -1.  As you can tell, the function can't exist at x = -1 because you'll have a 0 denominator.  So graphically, you'll have problems with that.  (You'll end up drawing an open circle at that point to indicate that it doesn't exist there.)