Horsepower is a unit of power created by James Watt in the 1700's. Who knew all these years later we'd still be using a unit he developed to compare steam engines to horsepower. We'll go through Watt's back of the napkin math, discuss in simple terms what horsepower means, and look at metric horsepower as well: PS, CV, and the many other abbreviations. Whether metric or imperial, horsepower as a unit makes no sense at all. We'll wrap up the video learning what unit we should actually be using.