Add +1 Button To your Site

There are any effect to your site after you add +1 button:

Effect on search result
+1 helps people discover relevant content—a website, a Google search result, or an ad—from the people they already know and trust. The +1 button appears on Google search, on websites, and on ads. For example, you might see a +1 button for a Google search result, Google ad, or next to an article you're reading on your favorite news site.

Adding the +1 button to pages on your own site lets users recommend your content, knowing that their friends and contacts will see their recommendation when it’s most relevant—in the context of Google search results. In addition, a user's +1's appear on the +1 tab of their Google Profile. While +1’s are always public, users can choose to make the +1 tab visible or invisible on their profile.

When a signed-in Google user is searching, your Google search result snippet may be annotated with the names of the user's connections who've +1'd your page. If none of a user's connections has +1'd your page, your snippet may display the aggregate number of +1's your page has received.

Effect on Site Performance
Content recommended by friends and acquaintances is often more relevant than content from strangers. For example, a movie review from an expert is useful, but a movie review from a friend who shares your tastes can be even better. Because of this, +1's from friends and contacts can be a useful signal to Google when determining the relevance of your page to a user’s query. This is just one of many signals Google may use to determine a page’s relevance and ranking, and we’re constantly tweaking and improving our algorithm to improve overall search quality. For +1's, as with any new ranking signal, we are starting carefully and learning how those signals affect search quality.

Effect on Google Crawl
When you add the +1 button to a page, Google assumes that you want that page to be publicly available and visible in Google Search results. As a result, we may fetch and show that page even if it is disallowed in robots.txt.

Effect to Traffic
Personalized annotations next to your page in search results may increase your site's visibility and make your site's snippet more compelling, which may in turn increase the odds that users will click through to your page.
To view how +1 affects your search traffic, you can use the +1 Metrics tool in Webmaster Tools. Available metrics include:

• Search impact: See the pages on your site that received the most impressions with a +1 annotation, and see how +1 annotations impact clickthrough rate (CTR).
• Activity: See the total number of +1's received by pages on your site.
• Audience: See aggregated information about people who have +1'd your pages, including the total number of unique users, their location, and their age and gender.

Show in Search Result
If a user +1's a URL on your site, the Google search result snippet for that URL may be annotated in search results and search add.

However, your site may make the same content available via different URLs. For example, your site may have several pages listing the same set of products. (More information about duplicate content.) One page might display products sorted in alphabetical order, while other pages display the same products listed by price or by rating.

For example:
http://www.example.com/product.php?item=swedish-fish&sort=alpha
http://www.example.com/product.php?item=swedish-fish&sort=price

If Google knows that these pages have the same content, we may index only one version for our search results. As a result, +1's for the other versions may not appear in search results.

You can make sure Google displays +1 annotations for the most search results possible by adding a rel="canonical" link to the section of the non-preferred versions of each page. This property should point to the canonical version, like this:


This tells Google: "Of all these pages with identical content, this page is the most useful. Please prioritize it in search results." Now, when a user +1’s a page with a non-canonical URL, Google will associate that +1 with the canonical, preferred version.More information about can onicalization.

Effect to Add
The +1 button itself will appear next to your headline on search ads. Personalized annotations will appear beneath your Display URL. For example, Maria +1's a page selling a neat laptop holder on a website. When a search ad with that same URL appears, her friend Sam might see the ad with the note "Maria and 28 other people +1'd this."

Adding +1 button
Yes, but you'll need to edit the button code. Use the href attribute to specify the target URL. For example, if your home page has a module linking to your blog, and you want to add a +1 button to that module, edit the value of the href attribute to point to your blog's URL, like this: