What's a Reynolds Number?

A reynolds number is a measure of turbulence of a fluid. You calculate the velocity of the fluid, and you can figure out theReynolds number based on different geometries. It's complicated, and it's very hard to explain. And i'm uncomfortable talking about it, because i have to go back and reference my books every time i do it myself. So i want to make sure i get it right,. t i meany and i am absolutely certain that i do not have a grasp on it.