Using NAND or NOR gates to make up Circuits
All other gates/functions can be implemented by NOR or NAND gates. so they are called universal gates. In fact, in chips, entire logic maybe built using only NAND (or NOR) gates.
inverter— nand with inputs shorted.
and —— nand followed by a inverter(using nand).
or——— giving inverted inputs to nand gate.