DeMorgan's Law was never fun in circuits (why use NOR, and NAND gates, when they made AND and OR gates)

1. NOR and NAND gates are cheaper than OR and AND gates; OR is implemented with a NOR followed by an inverter (NOT), and AND is likewise implemented with a NAND followed by an inverter. This saves on the delay and cost of the extra inverter.
2. It is possible to implement any circuit with only using NANDs, or only using NORs. The same can't be said for AND and OR.