Use NAND gate to make NOT gate

Picture of Use NAND gate to make NOT gate
Sometimes when you're building circuits, you dont always have the right components. Fortunately when it comes to digital logic gates, you can make the component you need! If you're fresh out of NOT gates, but have an extra NAND gate laying around, you're in luck! With a NAND gate you can connect the two inputs, then add your input, to effectively create a NOT gate! Its as simple as that! See picture for circuit diagram.

Well explained. NAND gate is one of the universal gates and it can also be used to build OR gate & AND gate. Follow the link: OR Gate, AND Gate, NOT Gate using NAND Gate to get more information.