The OR Gate

The OR gate is the third of the three fundamental logic gates. It takes two inputs and produces one output. The output is 1 (TRUE) when at least one of the inputs is 1. The output is 0 only when both inputs are 0.

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How the OR Gate Works

The OR gate checks whether any of its inputs are true. For a two-input OR gate:

• The output is 1 when Input A OR Input B (or both) is 1.
• The output is 0 only when both inputs are 0.

Think of the OR gate as a generous door policy — you can enter if you have a ticket OR if you are on the guest list OR if you have both. You are only turned away if you have neither.

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Truth Table for OR

Input A	Input B	Output (A ∨ B)
0	0	0
0	1	1
1	0	1
1	1	1