I create a simple web application in Netbeans, named WebApplication1. There is a file created, named index.jsp. When I run the app, browser goes to index.
it could be index.html or index.jsp the welcome page of your web application in Netbeans.
also there is a bug in Netbeans IDE 8.2 either : even if you make changes in the descriptor web.xml (by adding "welcome-file-list" tag), "Run" runs old version of your index!
to fix this, put './index.html' in 'Relative URL' field in the category "Run" in properties of your project.