Java Wildcard Types are used in generic programming to represent unknown types in a generic class or method. Wildcards enable flexibility when working with parameterized types, allowing developers to specify that a generic type can accept any type, a specific subtype, or a supertype. Java Wildcard Types are defined using the `?` symbol and can be used with bounds, such as `extends` or `super`, to further constrain the types. Introduced in Java 2004 with Java 5, wildcards help make Java generics more powerful and flexible.

https://docs.oracle.com/javase/tutorial/java/generics/wildcards.html