Best Horse Racing System

What are the different surfaces in horse racing like?-?

In horse racing, how many different types of surfaces are there? I know dirt and turf are traditional, with different grades of each, but now there polytrack, pro-ride, and who know what else? Is there evidence that the man-made surfaces are safer? Which types of horses do best on what surface? Clearly, my question(s) are broad in nature, I'd like to learn more about each.

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