Why are NAND and NOR gates categorized as universal gates?

NAND and NOR gates are categorized as universal gates because they have the ability to create any other type of logic gate—such as AND, OR, or NOT—when combined in various arrangements. This property of universality means that you can design an entire digital circuit using just NAND or just NOR gates, which makes them highly versatile in digital electronics.

For example, a NAND gate can be used to construct a NOT gate by simply connecting both inputs together. Additionally, a combination of NAND gates can be arranged to create an AND gate and further configurations can yield OR gates and other complex functions. Similarly, NOR gates can achieve the same by configuring them appropriately.

This unique quality allows engineers and designers to simplify the design and manufacturing of digital circuits, as they can rely on a single type of gate to build a variety of logical operations. Thus, the ability to form any other logic gate through combinations fundamentally solidifies the classification of NAND and NOR as universal gates.