The +1 button is nothing but an alternative to Facebook like button. But don't think it just like Facebook like button. It is something more than Facebook like button.
When you +1 something actually you're doing many things. Give a +1 to a post means you're recommending this post on Google Search, Sharing with your friends in your Google + Circle and most importantly you're saving the page in your +1 list.
In order to use the Google +1 button, you must have a Google Account. And the account should be visible to public. If you don't set your profile publicly visible then you will not be able to see and use +1 button.
Sometimes you may wanna save a copy of your favourite web page. But you don't need to do so if you use +1. If you see a +1 button in that web page then just give a +1 and you will find this page in your Google + profile at the +1 list!
