root or html

I have never figured out the rationale for warehousing all the files in
html folder.
So how do I access my site....
http://mysite.com/html/index.php
Some say to move all folders from html to htdocs or www whichever applies.
Others say to preserve relationships...
And nothing appears ever in guides and docs...why not?
Seems like there should be use root because...
or
preserve relationships options has these advantages....

Russell Griechen