Purpose - include where a login screen needed for 1.6
The screen may look slightly different on different sites, for the general appearance, the name and the position depends on how the site is designed.
There are separate boxes for entering your Username and Password.
When you have logged in you will probably be able to see more Menus and other content on the site. If you have the right permissions, you should also be able to edit some of the content. Look out for the edit icon