How can you restrict a property's access to only within its class?

To restrict a property's access to only within its class, the private keyword is employed in Kotlin. When a property is declared private, it becomes inaccessible from outside the class, which encapsulates the property and protects it from external modifications or access. This is fundamental in object-oriented programming, as it allows you to hide the internal workings of a class and only expose what is necessary through public methods.

The importance of this encapsulation means that the internals of a class can change without affecting code that uses the class, leading to more maintainable and less error-prone designs. In practice, using the private keyword is a standard way of ensuring that attributes of a class can only be interacted with through the class’s own methods, thus enforcing control over how these properties are accessed and modified.

In contrast, the other options serve different purposes, such as providing public access to properties or defining visibility within the same module, but they do not achieve the goal of restricting access exclusively to the class itself. The val keyword is used for declaring read-only properties, but it does not inherently provide access control.