The document discusses NAND gates and their ability to act as universal logic gates. It defines logic gates and universal logic gates. It then explains that a NAND gate produces an output that is false only if all its inputs are true, which is the complement of an AND gate. The document shows how NAND gates can be used to create NOT, AND and OR gates, demonstrating that all basic logic gates can be made using only NAND gates, giving it the title of universal gate.