Oh, hey: How a differential gear works in a car's transmission

Cars are a mystery to me. One peek under the hood spirals me into instant confusion. I understand there is an engine, which makes the car go. A battery also makes my car go, and lets me see at night and keeps the radio going. Brakes make me stop. Fuel comes from a fuel tank. The gas cap is toward the rear of my car, but the fuel gets to the engine in the front of my car, probably via a magical expressway populated by oil-stained Gasoline Gnomes.

Frank, honest and hard-working.

My dearest is far more knowledgeable. He knows how to check the levels of fluid and where to pour the various fluids. He can even change a fuel filter. This is magical to me.

Whenever I find a clear, concise explanation for how any part of a car works, I am thrilled. I want to know how my car works, even if I never do anything with what I'm learning about.

Without further ado, here is how a car part works.