Quoting from Techcrunch (http://techcrunch.com/2010/11/14/path-photo-sharing/)

"Path is a private photo sharing network - think Instagram, but without the filters and with a privacy model that takes away any anxiety associated with sharing photos with people you don’t know. It’s based around email addresses and phone numbers, rather than a public database of users. And compared to other popular social applications, Path is going against the grain: there’s no follow system and the friend system is also quite different from what you’re used to on Facebook."