Java has transformed remarkably over the years, introducing new features and enhancements to make the language more robust and secure. One such feature introduced in Java 15 as a preview is the 'sealed' keyword for classes and interfaces. It was included in Java 17 as a final feature. Sealed classes and interfaces provide improved control over the inheritance hierarchy. In this article, we will explore sealed class in Java & sealed interfaces, including their syntax, rules, code examples, and related concepts. What is a sealed keyword in Java? In Java, the sealed keyword is used to control and restrict the inheritance hierarchy of classes and interfaces. It allows us to specify which classes or interfaces are allowed to extend or implement a