There are other brands besides JBoss or Weblogic. You would need them
if that is all you have access to/can't pay for the licenses of the
other products. There are several free containers out there. JoNAS is
another free container. There are others out there as well. It just
takes searching them. JBoss is very well known however and so if you
are going to experiment, I'd recommend learning on JBoss and then
finding the best server that suits you in terms of features after you
decide what you will be doing with the application server and its EJBs.

Eclipse can embed JBoss or deploy to it via JBoss IDE Eclipse plugin
(IIRC)...(you can download it from the jboss web site).

Tomcat is a web server as others mentions. It can do JSPs and Servlets
(which is often sufficient) but for EJBs, you want an EJB "Container"
(like JBoss or Weblogic or something else like Websphere or iPlanet etc
etc.).

Tomcat has a manager app which can be used for deployment. Jboss also
comes with a manager application that can deploy modules as well.
Weblogic has a very nice facility for deployment via a web page on a
particular port. So it can all be done in a browser or an ant script
can be run from Eclipse (or outside Eclipse). I mean, there must be
thousands of ways to deploy but I've already suggested some very common
ways. You can search more about that and play with it on your own. It's
the best way to understand it. In particular read everything on the
jboss web site that you can and also on jakarta.apache.org 's Tomcat
project. ie: all the documentation is right there.

HTH,

John Gagon