In simple terms, PhantomJS is a web browser without a graphical user interface.

You’ll find couple of usage on internet like automation as it works with some automation tools etc and also handy for Dom manipulation, i like this tutorial #scotch.io

Before i used it to get page information on a cron and later taking screen shot and list image on CMS for A/B Testing.

 

its quite inserting to play on local so have a look at documentation

http://phantomjs.org/