Q:

How does Tomcat find the HOME PAGE of my Web App?

I am just getting started to learn about Web Apps and deploying them to Tomcat. So I started with a sample web app project - made up of struts, hibernate, etc., etc.
The ANT build was successful. Also, was able to deploy the web app through an xml under Catalina/host. I am able to open the web site with no issues.
This is the structure of my web app

-exploded

     -WEB-INF

          -classes

          -lib

          -web.xml

    -index.jsp

    -welcome.html

My question is
How does Tomcat know which is the first page / starting page / home page that it is supposed to open? Which file is this specified in?

A:

In any web application, there will be a web.xml in the WEB-INF/ folder. 
If you dont have one in your web app, as it seems to be the case in your folder structure, the default Tomcat web.xml is under TOMCAT_HOME/conf/web.xml
Either way, the relevant lines of the web.xml are
<welcome-file-list>
        <welcome-file>index.html</welcome-file>
        <welcome-file>index.htm</welcome-file>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>

so any file matching this pattern when found will be shown as the home page.
In Tomcat, a web.xml setting within your web app will override the default, if present.
Further Reading
How do I override the default home page loaded by Tomcat?

