Tagging Interfaces in Java

Question

What are tagging interfaces and what are they used for?

Answer 1

tagging interfaces are interfaces with no abstract methods inside , they are used to add a data type for the class which implements them and to be a parent interface for other interfaces ( especially with multiple inheritance in interfaces )

public interface name {} 
public interface john1 {} 
public interface john2 {}
public interface Demo extends john1 , john2 , name  {}

** when JVM sees the name interface , it will find out that the Demo will exert a specific cenario .