A NOT gate, also known as an inverter, is a fundamental digital logic gate that performs a logical NOT operation on a single binary input to produce a complementary binary output. In simple terms, it negates or flips the input signal. If the input is high (1), the output will be low (0), and vice versa.

The logic symbol for a NOT gate is represented as follows:

```
----
A | |
| NOT|
---| |
----
Output
```

In this symbol:

- A represents the input signal.
- The NOT symbol in the middle represents the logical NOT operation.
- The output is the complement of the input.

The truth table for a NOT gate is as follows:

A | Output |
---|---|

0 | 1 |

1 | 0 |

The truth table shows the output for both possible input values. As per the truth table, the output is the inverse of the input.

NOT gates are used in various digital applications, including:

- Inverting or complementing signals in logic circuits.
- Creating control signals that are the opposite of certain input conditions.
- Memory circuits to change the state of storage elements.
- Multiplexers and demultiplexers for signal routing.
- Clock signal generation and synchronization.

By integrating NOT gates with other logic gates, more complex logic functions and digital circuits can be designed to perform various tasks in digital devices and systems.