I am learning about car mechanics as a hobby. How a car works is a nice learning site. [1] Just learned about starter motors today. I didn't know it has gears

I am learning about car mechanics as a hobby. How a car works is a nice learning site. [1] Just learned about starter motors today. I didn't know it has gears too, in particular the planetary gear system, which is not mentioned in this tutorial. (I quickly skimmed through) [1] https://www.youtube.com/watch?v=VRe_hKxzKUg&t=1094s https://www.youtube.com/watch?v=VRe_hKxzKUg&t=1094s https://www.howacarworks.com/ https://www.howacarworks.com/