"Rate of change" refers to the slope of a line that connects the two points of the line. It is the ratio of the change in the y-coordinates to the change in the x-coordinates. This rate of change between the points (x1, y1) and (x2, y2) is given as (y2-y1)/(x2-x1). This Formula helps us to calculate the slope of a line if the coordinates of the points on the line are given.