NAND and NOR can be used to build logic circuits
NAND + NOR is physically easier to implement and more efficient than AND+OR
NAND: NOR:
NOT can be build from both gates : Boolean theorems
⇒ NAND ⇒ NOR
Using DeMorgan’s, we can implement any circuit from NAND (SoP) → This logic also applies to NOR → (PoS)