Drive Train Components: the inner working parts of a drive train

[naruto137]

So call me a noob but I am just wondering, what are the ways in which you can use components to drive your robot besides just using direct motor to wheel drive and what and why are the advantageous? (ie chains, gearboxes, etc)

I am mainly wondering about not the various drive trains, but the different components that can be used in the drive train, like how exactly gearboxes can be used, the types and such and how they would be advantageous, or how gears can be configured in a certain way and how that would help, or anything else like that.

Thanks!