Internet giant Google has gone ahead and added a social tinge to its search engine by unveiling what has come to be dubbed as challenge to Facebook's Like Button, a +1 button.

With this social search button, Google Inc allows people to personally endorse search results and Web pages, an important step in its efforts to add social networking capabilities to its products amid increasing competition from Facebook.

The +1 button will appear alongside Google search results for some users on Wednesday. The feature will enable users recommend specific search results to friends and acquaintances by clicking the button.

The +1 button, which has prompted headlines such as 'Google announces +1 Button in a challenge to Facebook's Like Button' on LA Times and G'oogle Looks to One-Up Facebook's 'Like' With '+1′ Button' on a Wired blog, comes a year after Facebook rolled out the Like button.

While the Facebook Like buttons were back then seen as a challenge to traditional search engine ranking algorithms for finding online information by analysts, Google's latest offering is largely being seen as a move to hold on the dissevering online ad revenue.

The social networking giant has been giving almost all major web players a run for their money. Microblogging site Twitter, which is also aiming at taking a bite off the online revenue, recently welcomed back its estranged co-founder Jack Dorsey to head products. Dorsey's ingenuity is expected to further boost the popularity of the site and get users to spend more time on Twitter consequently giving a boost to the ad revenue prospects.

Although Facebook has, evidently, managed to emerge as a serious threat to many players notwithstanding the nature of the competing services, there have been several signs in the past indicating that Google is lodged in an active war against the growing social networking site.

The foretokens to the search engine- social networking battle emerged early 2010 as Facebook had, to the surprise to many, begun to overtake Google in terms of traffic.

In January 2010, traffic analyst firm Hitwise revealed numbers on web activity in Australia, showing, For perhaps the first time ever, social networking sites have surpassed the traffic search engines receive. The following month, Facebook passed Yahoo! and was nearing Google in the #1 spot for most monthly unique visitors from the US, according to traffic analyst firm Compete.

In March 2010, Google Search accounted for 7.03 percent of US Internet visits, compared to 7.07 percent for Facebook, Hitwise said on its Analyst Weblog. In December 2010, a report on the annual trend showed that Facebook.com was the top visited website in the US in 2010, with 8.93 percent of site visits between January and November while Google.com came in second at 7.19 percent, Yahoo Mail third at 3.52 percent, Yahoo.com fourth at 3.30 percent and YouTube came fifth at 2.65 percent.

However, Google did not wait until the numbers made evident the reality of its slipping hold online. Three years ahead of the traffic numbers, Google had already begun its war against Facebook, despite having Orkut. In November 2007, Google announced OpenSocial. The service promised a common social platform in which widgets are written once for multiple platforms, allowing access across sites in a seamless manner. Facebook had just then launched a public search feature, which came to be considered as a move to grab traffic from Google.

Nevertheless, in 2010, Google felt the pinch of the growth of the social networking site like never before. In February 2010, Google launched Google Buzz to make its e-mail service, Gmail more social. Unveiling the attempt at a foray into social media, Google had explained that Buzz was conceptualized on the human need of sharing experiences and the social media phenomenon of wanting to share it in real time. Activation of buzz produced a social networking experience what could best be explained as a hybrid of Facebook and Twitter.

With Buzz not achieving the heights it was expected to, in July 2010, Google held talks with several makers of popular online games as it seeks to develop a broader social-networking service that could compete with Facebook Inc. Quoting sources close to the matter, Wall Street Journal reported that Google was in discussions with top developers, Playdom Inc., Electronic Arts Inc.'s Playfish and Zynga Game Network Inc. to offer their games on a new service it is building.

Amid continual efforts to produce a formidable rival to Facebook, Google also heated up the war by cutting Facebook's access to the key piece of the social graph with a simple tweak on its Terms of Service. The modification to the terms established that any service that accesses Google's Contacts API will need to offer reciprocity. Facebook did not offer reciprocity therefore losing out on Google's Contacts API, which makes it easy to import your list of friends' and coworkers' email addresses into another service.

The addition of the Terms of Service for the Contacts API, read: Google supports data portability. By accessing Content through the Contacts Data API or Portable Contacts API for use in your service or application, you are agreeing to enable your users to export their contacts data to other services or applications of their choice in a way that's substantially as fast and easy as exporting such data from Google Contacts, subject to applicable laws.

The war spilled over to 2011 with Facebook using its power to exclude Google from its advertiser list. In February 2011, Facebook formally announced that developers would soon only be able to work with a pre-selected advertising vendor list when running ads within applications. The following month, March 2011, news emerged of Google not being included in Facebook's new preferred advertiser list. The omission was set to hit developers depending on Google to generate their ad revenue.

Now, Google has taken a rather unexpected step in the ongoing war against Facebook by introducing a social element on its search engine. Although the feature had inspired arguments as to why it is a bad idea, Google has launched the button right after the Internet giant was faced with anticipation over a rumored social networking offering, 'Google Circles' in mid-March.