What is the ternary operator?

In PHP, the ternary operator, also known as the conditional operator, provides a concise way to make decisions and assign values based on a condition. It is a shorthand way to write simple “if-else” statements in a single line of code.

The ternary operator has the following syntax:

```php
(condition) ? true_expression : false_expression;
```

Here’s how it works:

1. Condition: The expression inside the parentheses is the condition you want to evaluate. If this condition is true, the operator returns the value of `true_expression`; otherwise, it returns the value of `false_expression`.

2. True Expression: This is the value that gets assigned if the condition is true.

3. False Expression: This is the value that gets assigned if the condition is false.

Example:

```php
$age = 18;
$isAdult = ($age >= 18) ? true : false;
```

In this example, the ternary operator checks if the variable `$age` is greater than or equal to 18. If it is, it assigns `true` to `$isAdult`; otherwise, it assigns `false`. 

The ternary operator is especially useful when you need to assign values to variables or properties based on a simple condition, making your code more concise and readable. However, it’s important to use it judiciously and not overly complicate code logic, as more complex conditions are often better suited for traditional “if-else” statements.