What is slope or gradient?
Slope measures how steep a line is. It is the vertical change divided by the horizontal change, often described as rise over run.
Slope formula explained
For two points, m = (y2 - y1) / (x2 - x1). The numerator is the rise and the denominator is the run.
Positive, negative, zero, and undefined slopes
Positive slopes rise left to right, negative slopes fall, zero slopes are horizontal, and undefined slopes are vertical because the run is zero.