Apache Jakarta Project says, this is the top-level entry point of the documentation bundle for the Tomcat 4 Servlet/JSP container. Tomcat 4 implements the Servlet 2.3 and JavaServer Pages 1.2 specifications from Java Software, and includes many additional features that make it a useful platform for developing and deploying web applications and web services. (a) Servlet 2.3 provides Web developers with a simple, consistent mechanism for extending the functionality of a Web server and for accessing existing business systems. A servlet can almost be thought of as an applet that runs on the server side–without a face. Java servlets make many Web applications possible. Servlets are the Java platform technology of choice for extending and enhancing Web servers. Servlets provide a component-based, platform-independent method for building Web-based applications, without the performance limitations of CGI programs. And unlike proprietary server extension mechanisms (such as the Netscape Server API or Apache modules), servlets are server- and platform-independent. This leaves you free to select a “best of breed” strategy for your servers, platforms, and tools. (b) JavaServer Pages 1.2 technology enables Web developers and designers to rapidly develop and easily maintain, information-rich, dynamic Web pages that leverage existing business systems. As part of the Java technology family, JSP technology enables rapid development of Web-based applications that are platform independent. JSP technology separates the user interface from content generation, enabling designers to change the overall page layout without altering the underlying dynamic content. Read more.