# Not operation

Learn how to negate a boolean value.

The logical not operation inverts a boolean value. It is typically used to invert a condition or negate the result of an expression.

A negation is denoted by the `!` sign before an expression:

```cql
!/*<value>*/
```

Here is a practical example:

```cql
!true // false
```

You can also use `not` for a more readable alternative:

```cql
not /*<value>*/
```

In the above examples, the boolean value `true` is negated, resulting in `false`, as the following expression attests:

```cql
not true is false
```