In mathematics, the slope or gradient of a line is a number that describes both the direction and the steepness of the line. Slope is often denoted by the letter m.

• The direction of a line is either increasing, decreasing, horizontal or vertical.
  • A line is increasing if it goes up from left to right. The slope is positive, i.e. .
  • A line is decreasing if it goes down from left to right. The slope is negative, i.e. .
  • If a line is horizontal the slope is zero. This is a constant function.
  • If a line is vertical the slope is undefined (see below).
• The steepness, incline, or grade of a line is measured by the absolute value of the slope. A slope with a greater absolute value indicates a steeper line