SlopeFrom Wikipedia, the free encyclopediaThe slope is commonly used to describe the measurement of the steepness, incline, or grade of a straight line. A higher slope value indicates a steeper incline. 

Line with a low slope value

Line with a high slope value

The slope is defined as the ratio of the "rise" divided by the "run" between two points on a line, or in other words, the ratio of the altitude change to the horizontal distance between any two points on the line. It is also always the same thing as how many rises in one run. 

"Slope equals rise over run" 

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Text from: http://en.wikipedia.org/wiki/Slope, February 13, 2007 