Tomcat ?? Where to get it

Hi All, I have to learn how to use a Java based web portal that will run on most web servers. To run on Linux it needs to have Java on Apache, I have been advised that it is better to use something called Tomcat. Could someone please direct me to where I can find out some more information on Tomcat. Thanks in advance. Shane Broomhall Brisbane Australia shanebroomhall@computer.org shanebroomhall@airforce.net