The +1 button works in a two-way manner. With this, users can share pages they like, find useful, or want to recommend for possible future use to others. This can be done within their circles, restricted to people viewing the +1ed pages in the profile or it can be shared with everyone.
The other way round, this button helps improve the Google search process by showing +1 recommendations in a separate category in the search results. Thus, users can refine and simplify their search process by seeing what pages from their search have been +1ed.
Users can also control the visibility of their +1s. They can easily change the settings to restrict the visibility to a select number of circles, while blocking a few. Also, +1s can be kept hidden in the profile where no one will get a view of a user’s list, while they remain publicly visible.
According to the update, the Google +1 button will appear automatically to anyone using Android version 2.1 or above and iOS 4.0 or higher browsers.