The Symbol NAND Gate is an AND gate followed by NOT gate. The term NAND is a contraction of AND+NOT.
The NAND gate has two or more inputs and a single output. The NAND produces HIGH when any of the inputs is LOW.
The functions involve only three operations which make up Boolean algebra: AND, OR, and COMPLEMENT.
This operating power supply is 5VDc. They are symbolically represented as follows:
These operations are like ordinary algebraic operations in that they are commutative, associative, and distributive.
There is a group of useful theorems of Boolean algebra which help in developing the logic for a given operation.

NAND GATE ANIMATION

Operation:-
CASE-1. Input A,B is LOW then output HIGH.
CASE-2. Input A is LOW B, High then output HIGH.
CASE-3. Input A is HIGH B, Low then output HIGH.
CASE-4. Input A,B is HIGH then output LOW.
LOGIC EXPRESSION:–
The input variables are A,B and the output variable Y is then the logic expression for NAND gae is Y = AB Inverted output. NAND GATE used as an universal gate. PACKAGE:-(TTL) Transistor Transistor Logic.