Set up proper URL directory structure for web pages

Many websites use the following format for different pages throughout the site.

For example: http://ift.tt/2amWeNH

The about page URL is: http://ift.tt/2alXqNU

Currently my about page URL is http://ift.tt/1n43jzn

The URL looks much cleaner and better using the the folder structure website.com/about/

I just wanted to figure out whats the proper way web developers set this up for their website for other pages.

Do they really make a about folder in the root directory and use a index.php for the about page? So whenever they open the /about/ directory it automatically loads the index.php file for that particular page?

Thanks for any help just trying to use proper etiquette for my site