The Negated AND, NO AND or NAND gate is the opposite of the digital AND gate

AND gate

The AND gate is a basic digital logic gate that implements logical conjunction - it behaves according to the truth table to the right. A HIGH output results only if both the inputs to the AND gate are HIGH . If neither or only one input to the AND gate is HIGH, a LOW output results...

, and behaves in a manner that corresponds to the opposite of AND gate, as shown in the truth table on the right. A LOW output results only if both the inputs to the gate are HIGH. If one or both inputs are LOW, a HIGH output results.

The NAND gate is significant because any boolean function can be implemented by using a combination of NAND gates.