What are the standard shifter designs and mechanisms? What are the standard shifting methods?  I only know the shifting dial on flat bars and the old fashioned levers on ten speeds.  I'm not asking about when to use a particular gear but the mechanics of shifting methods.  Thanks.
With the exception of the new electronic stuff, every shifter out there that isn't the old friction style works on a ratchet and spring mechanism to index the amount of cable being pulled or released. Is that what you are asking?