What are Setters in Object-Oriented Programming?

In object-oriented programming, a setter is a method that sets the value of an object's property. It is called when you assign a new value to the property.

For example, let's say you have a class `Person` with a property `name`:
```
class Person {
private $name;

public function __construct($name) {
$this->name = $name;
}

public function setName($newName) {
$this->name = $newName;
}
}
```
In this example, the `setName()` method is a setter for the `name` property. It takes a new value as an argument and assigns it to the `name` property.

Setters are useful when you want to control how the value of a property is set, or when you want to perform additional actions when the value of a property changes. For example, you might use a setter to validate the input before assigning it to the property, or to trigger a change event that other parts of your code can listen for.

It's worth noting that not all properties need setters. If a property does not require any special logic or validation when its value is set, you may choose to omit the setter method and simply assign the value directly in the constructor or elsewhere in your code.