At first, I have not heard about g+ (Google Plus) and the very first social network I have joined before is Facebook.
Signing in for a G-mail account gives everyone access to Google Plus since Google has this "one account for all accounts" - Youtube, Blogger, and G-mail are all Google's property. You are instantly given privilege to edit an automatically existing g+ account that is why I learned it. I am curious about the little icons at the top of my g-mail account seeing the g+ button wonder what is it for.