Explain the concept of Marker Interface and how it is used in programming.

Marker Interface is an interface without methods and fields, used for marking or indicating a class with a certain property or behavior. In programming, it is used to pass metadata about the class at compile time or runtime.

For example, in Java, the Serializable interface is a marker: it contains no methods, but its implementation tells the JVM that objects of the class can be serialized.

Example:

public interface Serializable {
    // No methods
}

public class User implements Serializable {
    private String name;
    private int age;
    // getters, setters, etc.
}

Using a Marker Interface allows frameworks or libraries to check for the presence of the interface via instanceof and perform special actions (e.g., serialization, cloning, security).