Logic Gates and Boolean algebra
An electronic circuits which are designed to represent the logical expression are known as logic circuits or logic gates (ORGate, AND Gate, NOT Gate, NORGate, NAND Gate, XOR gate and XNOR Gate). A Boolean algebra deals with the Boolean value that is either 1 or 0.
Logic Gates
OR Gate
It is a logical gate that receives two or more input signals and generates the only one output signal. It produces output signal as true when any one of the input signal is true otherwise it produces output signal as false.
The ORGate logical expression for two inputs A and B is given below.
Q=A+B
The ORGate Symbol and Truth Table is shown in figure.
Symbol 
Truth Table

AND Gate
It is a logical gate that receives two or more input signals and generates the only one output signal. It produces output signal as true when all of the input signals are true otherwise it produces output signal as false.
The ANDGate logical expression for two inputs A and B is given below.
Q=A . B
The ANDGate Symbol and Truth Table is shown in figure.
Symbol 
Truth Table

NOT Gate
It is a logical gate that receives only one input signal and generates the inverted version of input signal. It is also known as Inverter Circuit Gate.
The NOTGate logical expression for two input A is given below.
Q= A’ (Complement of A)
The NOTGate Symbol and Truth Table is shown in figure.
Symbol 
Truth Table

NOR Gate
It is a logical gate also known as NOT OR gate. It produces output as the complement of ORGate. The output of the NORGate is false if any one of the input signal is true and output is true if all input signals are false.
The NORGate logical expression for two inputs A and B is given below.
Q=(A+B)’
The NORGate Symbol and Truth Table is shown in figure.
Symbol 
Truth Table

NAND Gate
It is a logical gate also known as NOT AND gate. It produces output as the complement of ANDGate. The output of the NANDGate are true if any one of the input signal is false and output is false if all input signals are true.
The NANDGate logical expression for two inputs A and B is given below.
Q=(A.B)’
The NANDGate Symbol and Truth Table is shown in figure.
Symbol 
Truth Table

XOR Gate
It is a logical gate also known as Exclusive OR gate. It receives two or more inputs and produces output that performs exclusive disjunction. The output of the XORGate is true only when exactly one of the input signal is true otherwise the output is false.
The XORGate logical expression for two inputs A and B is given below.
Q=A’.B+A.B’
The XORGate Symbol and Truth Table is shown in figure.
Symbol 
Truth Table

XNOR Gate
It is a logical gate also known as Exclusive NOR gate. It receives two or more inputs and produces output as the complement of XOR Gate. The output of the XNXORGate is true only when all of the input signals are true or all of the input signals are false otherwise the output is false.
The XNORGate logical expression for two inputs A and B is given below.
Q=A.B + A’.B’
The XNORGate Symbol and Truth Table is shown in figure.
Symbol 
Truth Table

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