Change the port to 80. Edit install_dir/conf/server.xml and change the port attribute of the Connector element from 8080 to 80. Turn on servlet reloading. Edit install_dir/conf/context.xml and change <Context> to <Context reloadable="true" privileged="true">. Enable the invoker servlet. Go to install_dir/conf/web.xml and uncomment the servlet and servlet-mapping elements that map the invoker servlet to /servlet/*. Turn on directory listings. Go to install_dir/conf/web.xml, find the init-param entry for listings, and change the value from false to true.
Most people will just want to download the preconfigured Tomcat version, set JAVA_HOME and CLASSPATH, and they are done. But following is a summary of the steps for people who want to change the configuration or do it themselves.
Those extra steps make changes to the standard configuration, and are entirely optional.
Originally posted by pooja jain: why do we need all these?
You don't need them but I'm sure if you looked at each of the configuration changes you'll be able to imagine how they might be useful to someone in a development environment.
With the 'reloadable' attribute set to true, Tomcat will watch your class files and automatically reload the application if one of them is updated (preventing you from having to restart the app every time you compile something).
Turning on directory listings makes it easy for you to see what files are in a particular directory (as long as a welcome-file is not configured).
The InvokerServlet allows a developer (in a test or development environment) to run servlets without having to declare and map them in the deployment descriptor (read the link to find out why using this technique can cause a lot of features to fail. Many of us feel there is never a good reason to use the InokerServlet).