JSP and Servlets are the core J2EE technologies for server-side web applications. JSP (JavaServer Pages) handles the presentation layer with dynamic content generation, while Servlets manage the request/response processing and business logic. This combination directly parallels PHP's server-side scripting role, making it the natural replacement. Applets are client-side Java programs, while EJBs handle enterprise business logic and transaction management - unnecessary for simple PHP replacement.