I'll be buying a new phone soon. And I'll probably go with the Nexus 6. I was curious if Nethunter is a full operating system and thus replaces the android operating system or if it's more like an "app". I would be using this phone for daily use, and therefore it would be a waste of money if I can't just use the phone as a normal phone.
I have read that it's an application on your android device somewhere on an article but I want to be sure before investing in a not so cheap phone.

Thanks in advance