Java Servlets are server-side modules, typically used to process requests and send back responses in web applications. Servlets are useful for handling requests that do not generate large HTML markup responses. They are typically used as controllers in Model View Controller (MVC) frameworks, for forwarding/redirecting requests, or for generating non-HTML responses, such as PDFs. To generate HTML response from the servlet, you need to embed HTML code (as a Java String) in Java code. Therefore, it is not the most convenient option for generating large HTML responses. JEE 8 contains servlet API 4.0.