What happens behind the scene when we create new Web Application in SharePoint?

When we create a new Web Application in SharePoint, following are various actions which happens behind the scene:

1. Creates a unique entry in SharePoint configuration DB for the Web Application and assign GUID to that entry.
2. Create and configures a new site in IIS
3. Creates and configures a new IIS application pool.
4. Configures authentication protocol and encryption settings.
5. Assign a Default alternate access mapping for the Web Application.
6. Creates the first content database for the Web Application.
7. Associate a search service with the Web application.
8. Assign a name to the Web application that appears in the Web application list in SharePoint Central Administration.
9. Assign general settings to the Web application, such as maximum file upload size and default time zone.
10. Updates the web.config file to make entries for custom HTTP Modules andHandlers for SharePoint.
11. Creates virtual directories for SharePoint web services and SharePoint layouts folder.

After creating a Web Application in SharePoint, the web site is actually not created yet. It means if you try to access the Web Application using the web app url, it will show you "Page cannot be displayed" error. Basically at this point of time, a web application has been created and all the mandatory configuration has been done. Now the next step is to create a Site Collection using a particular Site Definition, then only the actual site will be created and you will be able to access the site using the url of Site Collection.