Google +1 is an initiative from Google that is an indication towards making the search engine more social. If Facebook has its “like”, then Google has created its new feature as its equivalent. The +1 button will be displayed along with all the ads and search results, and they are linked with your Google profile. The objective of this new feature is to gather the data of the sites that have been +1’d by people you know and it would be used to customize search results.
If you want to recommend anything on the web, you have to click on +1 besides the ad or the webpage. And, then the +1s get displayed on search results on Google.
In order to add the +1 button to your site, you would have to copy and paste the relevant snippet code to your site. An ideal location is besides the sharing links, close to the page title or above the fold (the place where users have to scroll down the page). It would also be beneficial if the Google +1 button is placed at the start and end of a story or article.
Since Google +1 is public in nature, the button must be added to pages that are public and accessible to crawlers. And, when the button is placed, Google crawls the page once or several times in order to store the title and content of the page, corresponding to the +1 button click.
The social network of Google +1 comprises of friends from Google Talk, My Contacts in Gmail, and users followed in Google Buzz and Google Reader, and other services like Flickr and Twitter are also being connected.
When a user +1s a link on your website, the snippet for the link gets annotated in search ads and search results. Your website will also make the content available through various URLs. For instance, there may be many pages on your site that list one type of product. While one of the pages displays the products alphabetically sorted, others may display them sorted according to rating or price. And, in case Google comes to know that all these pages list the same content, only one of the versions may be indexed in the search results. Therefore, there is a chance that the Google +1 for different versions of the same content may not display in the search results.