Appendix A. Apache Tomcat
The Tomcat servlet engine is an open-source package developed as part of the Apache Software Foundation's Jakarta project. It is the official reference implementation for both the servlet and JSP specifications. However, it's not just a research project; it's capable of being deployed in production environments and offers many of the same features as commercial Web application containers.
Tomcat can act as a stand-alone Web server and also as a servlet/JSP engine for other Web servers. When you download the Tomcat server, you really get a number of packages. Catalina and Jasper are the names of the servlet and JSP containers. Tomcat also includes tools for administering the server and applications. Tomcat even comes in a version that can be embedded into other applications.
Don't Forget to Install the JDK
To use Tomcat, you need a full Java Development Kit (JDK) installed on your system. The smaller Java Runtime Environment (JRE) does not include a Java compiler, which is necessary for compiling JavaServer Pages. If you get an error telling you there is no compiler, you probably have the JRE edition.