A directory index file is the default page the server will display to the browser when no page is defined in the URL.

You can have more than one index file in each directory; the server will decide which index file to display based on the order listed in the default server configuration. You can find the order listed in this article here.

In some cases, your application may use a default page that is not already pre-configured in the default document list on the server. If this is the case, then you will need to tell the server what page is your index page using the following methods:

Specifying the default page for Unix hosting

1. Create a .htaccess file with a text editor and the following lines to specify the default page:
   

   DirectoryIndex filename.html

2. Save and upload the .htaccess file to the document root of your site or to any folders where you need to change the default document that is loaded when the folder is accessed.

Specifying the default page for Windows hosting

1. Login to the Plesk Server Administrator.
2. Select the domain name you wish to modify
3. Click on the Web Directories button.
4. Click on the Preferences icon
5. Type in your default document filename into the 'Default documents search order' box and click Add
6. Find the added document a the bottom of the list and click the Up button to move your document to the highest preference in the list.
7. Click OK to save changes