The Google +1 button introduced by Google helps you highlight valuable content on websites, in Google search results and ads, and also allows you to share good content with your circles on Google+. Google calls the +1 button shorthand for ‘this is pretty cool’ or ‘you should check this out’. The +1 button is very similar in functionality to the popular ‘like’ button from Facebook.

You can do the following with a Google +1 button -

1. Recommend good content in Google search results.

2. Vouch for good content from non-Google websites

3. Share content with your Circles on Google+.

When you share content with your circles, you can personalize it with your comments about the content.

4. Recommend Ads by Google

When ever you +1 something, it gets associated with your Google profile (provided you are logged into a Google account while +1’ing). Information on your Google profile, the +1′ed URL, your IP address, and related browser information is sent to Google. Do bear in mind, +1′ing something is completely a public activity, and people across the web will be able to see your recommendation when they are searching on Google or if they visit the +1′ed website.

How your +1′ed content will appear across the web -

1. Once you recommend content on Google search results, the next time a friend from your Google+ circles and Google contacts searches for the same term, your recommendation will pop up in the search results as an annotation along with the link.

People from outside your Google circles and contacts will only see an aggregate of the total +1′s for the content in the Google search results.

2. If you have shared content with your circles on Google+, it will appear in the streams of your friends.

3. If you have +1′ed an ad by Google, friends from your Google+ circles or Google contacts will be able to see your recommendation as an annotation.

Additional information on the Google +1 button -

1. Clicking on a +1 on a non-Google site does not share your profile information with the site. As a matter of fact, Google acts as an intermediary between you and the publisher by simply providing the +1 facility to both.

2. If you +1 something, the plus one button will turn to blue confirming your recommendation. If you want to undo your +1, you just need to reclick on the same +1 button again, and the button turns back to its normal color.

3. You will be able to see all your +1′ed content on the +1 tab of your Google profile as well as in Google+. The +1 tab on your profile is visible only to you unless you choose to make it public.

4. Webmasters can view how the +1′s affect their search traffic in the +1 Metrics tool in Google Webmaster Tools.

5. Google may crawl or recrawl pages in response to a +1 clicks in them.