/diy/ - Do It Yourself

Can someone double-check my comprehension of diodes real quick?
I'm trying to figure out why we need so many different parts to a diode/transformer thingy.
Because a practical diode (specifically a halfwave and a fullwave center tap) has too much variation in voltage due to its wave-like nature with occasionally reverse+forward (for DC), a way to reduce that voltage variation is to add in a filter, and the filter is done through a capacitor that 'ups' the minimum voltage from zero to a certain point above zero where it discharges to when a practical diode would've otherwise been zero because of the sin-wave thingy. And then to further simplify it, we add in a voltage regulator which is done through the form of a Zener diode?