Slope
The steepness of a line — its rise over its run.
The slope m of a line measures how quickly y changes as x changes. For two points (x₁, y₁) and (x₂, y₂) on the line, m = (y₂ − y₁) / (x₂ − x₁). A vertical line has undefined slope; a horizontal line has slope 0.
Formula
m = (y₂ − y₁) / (x₂ − x₁)