The difference quotient can be described as the formula for finding the slope of a line that touches a curve at only two points (this line is called the secant line). If we are trying to find the slope of a perfectly straight line, then we use the slope formula, which is simply the change in "y" divided by the change in "x". This is very accurate, but only for straight lines. The difference quotient, however, allows one to find the slope of any line or curve at any single point. The difference quotient, as well as the slope formula, is merely the change in "y" divided by the change in "x". The only difference is that in the slope formula, "y" is used as the y-axis, but in the difference quotient, the change in the "y"-axis is described by f(x). (For a detailed description, see the following section.)