A digital circuit having one or more input signals but only one output is called a logic gate or simply a gate. Logic gates are the basic building blocks of any digital systems.

The table which shows different combination of input along with their possible outputs is called truth table. Moreover, truth table will help us to find out the exact output of the inputs for different gates i.e AND gate OR gate and NOT gate.

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The table which shows different combination of input along with their possible outputs is called truth table. Moreover, truth table will help us to find out the exact output of the inputs for different gates i.e AND gate OR gate and NOT gate.

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**Basic AND Gate**

The AND gate has two or more inputs and a single output. The AND gate provides a high output only when all inputs are high. AND gate performs logical multiplication as a function.

**Truth Table**

Input Output

A B Y=A.B

0 0 0

0 1 0

1 0 0

1 1 1

**Boolean Equation**

Y=A.B

## Basic OR gate

The OR gate will have two or more inputs and a single output. The OR gate provides a high output if any or all inputs are high. The AND gate performs logical addition, more commonly known as OR function.

**Truth Table**

Input Output

A B Y=A.B

0 0 0

0 1 1

1 0 1

1 1 1

**Boolean Equation**

Y= A+B

## Basic NOT gate

The not gate will have only one input and one output. The NOT gate provides high output if an input is low. It provides the low output if an input is high. The NOT gate performs a basic logical function called inversion or complementation.

Most commonly NOT is also called as an inverter because output state is always opposite to input state.

**Truth Table**

Input Output

A Y=A'

0 1

1 0

**Boolean Equation**

Y = A'