OR gate :-  OR gate generates high output signal if any of it’s input signals is high.It has n input and 1 output.
                    For a 2-input OR gate,if A and B are the input signal then output signal Y can be represented as Y= A+B .
This gate is represented as :
                
Truth Table for OR gate :   

Tips- You can see in the table that  we get 1 if any one of A or B or both are 1.