Tomcat and default welcome page

I was trying to setup a quick website in my machine and installed tomcat and invoked it from browser as http://hostname it wasn't serving anything. Then I realised I had to add this block in web.xml

   index.html
   index.htm
   index.jsp

browser I added it and added an index.html and it still didn't work. Then I looked at webapps folder and saw a folder ROOT and added index.html there and it started serving home page!