There are mainly three parts of Logic gates

(1)          The 'OR' gate

(i) It has two inputs (A and B) and only one output (Y)

(ii) Boolean expression is Y = A + B

(iii) Given below the Truth table and logic symbol

(2)          The 'AND' gate

(i) It has also two inputs and one output.

(ii) Boolean expression is Y = A • B

(iii) Given below Truth table and logic symbol:

(3)          The 'NOT' gate

(i) It has only one input and only one output

(ii) Boolean expression is  Y=A

(iii) Given below Truth table and logic symbol: