JSP is also a Servlet.
Here's a good explanaton I got from one of the PhilJUG members and he is Miguel Juteau.
Hope this would help you.
"To be exact, a jsp is a mark up document that will be turned automatically into a servlet by a servlet/jsp
container such as TomCat, Jrun or Resin.
That's precisely why jsps were created: they are centered on presentation, very similar to a plain html
page. Then all the html tags in the jsp are turned automatically into out.print() statements in the generated servlet.
There are many other powerful jsp features, especially the possibility to instantiate and manipulate JavaBeans in a jsp. This allows you to pack discrete amounts of java code into beans that are used by the jsp, thus
keeping the jsp uncluttered and achieving the much desired separation of logic and presentation."