The Magic Of Tapers

WTF is a Taper and how does it apply to firearms? Specifically barrels, muzzle devices and silencers / suppressors? Well, they are a marvel of physics and do some great things for us.

Like how about creating alignment so that you don't have baffle strikes? Or sealing off gasses so that you don't gum up your threads or choke yourself out when shooting suppressed? Not to mention how they interact with each other. Making it so that all you need for a solid lock up is some good threads, some tapers and a little torque...