Yahoo on Monday made good on its promise to sue Facebook, alleging in a complaint that Facebook violated 10 patents. 
 
 The complaint, filed in the U.S. District Court in San Jose, Calif., makes a case that Yahoo innovated on several fronts, including messaging, news feed generation, social commenting advertising display, preventing click fraud and privacy controls. 
 
 "Facebook was not launched until 2004, 10 years after Yahoo was founded," the complaint reads. "Facebook has since grown to be one of the most widely trafficked sites on the Internet. That growth, however, has been based in a large part on Facebook's use of Yahoo's patented technology." 
 
 The complaint also quotes Facebook CEO Mark Zuckerberg as acknowledging that "getting there first is not what it's all about." Further on, it states, "Facebook's entire social network model, which allows users to create profiles for and connect with, among other things, persons and businesses, is based on Yahoo's patented social networking technology." 
 
 Yahoo's suit, which seeks unspecified damages, comes at an awkward time for Facebook. The social networking giant is expected to launch an IPO in May to raise $5 billion. Yahoo, meanwhile, risks being seen as desperate in engaging in patent trolling as its revenues and market share continue to slip. 
 
 The suit comes after Yahoo and Facebook were apparently unable to work out an agreement over the issue. Yahoo was in talks with Facebook over its patent claims last month, according to a report in The New York Times. At the time, Yahoo was threatening a lawsuit if Facebook didn't pay licensing fees, according to the report. 
 
 Image courtesy of Flickr, Eric Hayes 
 
 Complaint for Patent Infringement ||||| The Yahoo! Connected TV booth is shown during the 2011 International Consumer Electronics Show (CES) in Las Vegas, Nevada in this file photo taken January 7, 2011. Yahoo Inc sued Facebook Inc on Monday over 10 patents that include methods and systems for advertising on the... 
 
 SAN FRANCISCO Yahoo Inc sued Facebook Inc over 10 patents that include methods and systems for advertising on the Web, opening the first major legal battle among big technology companies in social media. 
 
 The lawsuit, filed in a San Jose, California federal court on Monday, marks a major escalation of patent litigation that has already swept up the smartphone and tablet sectors and high-tech stalwarts such as Apple Inc, Microsoft Corp and Motorola Mobility Holdings Inc. 
 
 Yahoo's patent lawsuit follows Facebook's announcement of plans for an initial public offering that could value the company at about $100 billion. 
 
 Facebook spokesman Jonathan Thaw said Facebook learned of the lawsuit through the media. 
 
 "We're disappointed that Yahoo, a longtime business partner of Facebook and a company that has substantially benefited from its association with Facebook, has decided to resort to litigation," he said. 
 
 In an emailed statement, Yahoo said it is confident it will prevail. 
 
 "Unfortunately, the matter with Facebook remains unresolved and we are compelled to seek redress in federal court," the company said in a statement. 
 
 Yahoo, one of the Web's pioneering companies, has seen its revenues decline in recent years at a time when rivals such as Facebook and Google have thrived. In January, Yahoo appointed former PayPal President Scott Thompson as its new chief executive, replacing Carol Bartz, who was fired in September. 
 
 Yahoo said late last month it was seeking licensing fees from Facebook over its patents and that other companies have already agreed to such licensing deals. 
 
 IPO COMPANIES VULNERABLE 
 
 Colleen Chien, a professor at Santa Clara Law in Silicon Valley, said companies are usually more vulnerable to patent suits when they are in the IPO process. 
 
 "As a general proposition, when a company is about to go public, the last thing it needs is to get involved in a knock-down, drag out litigation fight," Chien said. 
 
 "So that might make Facebook more willing to resolve its differences with Yahoo." 
 
 Yahoo has used similar timing to its advantage in the past. Google agreed to issue shares to Yahoo nine days before Google went public in 2004 in exchange for a license to Yahoo's patents. Google later took a $201 million non-cash charge related to the transaction. 
 
 In deciding to sue Facebook, Yahoo has retained the same law firm, Quinn Emanuel Urquhart & Sullivan, used by Google and other manufacturers in many Android-related smartphone patent cases. Google is a player in social media with its Google+ service. 
 
 Quinn Emanuel also counts social gaming service Zynga Inc as a client, according to the law firm's website. 
 
 Yahoo has not said whether it will bring patent claims against other social networking companies and a Google spokesman declined to comment on Quinn Emanuel's involvement. Zynga also declined to comment. 
 
 In the lawsuit, Yahoo says Facebook was considered "one of the worst performing sites for advertising" prior to adapting Yahoo's ideas. 
 
 "Mr. Mark Zuckerberg, Facebook's founder and CEO, has conceded that the design of Facebook is not novel and is based on the ideas of others," the lawsuit said. 
 
 ONLINE ADVERTISING 
 
 Only two of the 10 patents at issue are directly related to social networking technology. Most focus on online advertising, including methods for preventing "click fraud," as well as privacy and technology for customizing the information users see on a Web page. 
 
 "If what Yahoo is saying is literally true, then it seems like a lot of companies would be liable," said Shubha Ghosh, a professor who specializes in intellectual property at The University of Wisconsin Law School. But he added, much would depend on whether a judge defines the patents broadly or narrowly. 
 
 Several social networking companies, including Facebook, have seen an uptick in patent claims asserted against them as they move through the IPO process. 
 
 However, most of those lawsuits have been filed by patent aggregators that buy up intellectual property to squeeze value from it via licensing deals and none by a large tech company such as Yahoo. 
 
 The lawsuit is a change for Yahoo because the company has never initiated offensive patent litigation against such a large publicly traded company, according to a search of federal court dockets on legal database Westlaw, a Thomson Reuters unit. 
 
 A classic defense for companies targeted with patent claims is to threaten a countersuit using its own patents. But Yahoo possesses far more patents than Facebook. According to a U.S. government database, Yahoo has over 3,300 patents and published patent applications, while Facebook has 160. 
 
 The case in U.S. District Court, Northern District of California is Yahoo Inc. v. Facebook Inc., 12-cv-1212. 
 
 (Reporting By Dan Levine and Alexei Oreskovic; editing by Andre Grenon) ||||| Dow Jones Reprints: This copy is for your personal, non-commercial use only. To order presentation-ready copies for distribution to your colleagues, clients or customers, use the Order Reprints tool at the bottom of any article or visit www.djreprints.com 
 
 Yahoo Inc. watched in recent years as Facebook Inc. stole the attention of Web users and grabbed a major share of the online-advertising market. Now it is fighting back in court. 
 
 The faded Internet behemoth on Monday filed a suit against Facebook, alleging that the social-networking service got a "free ride" by violating 10 Yahoo patents covering technologies such as online advertising, privacy controls and messaging. 
 
 The move by Yahoo's new chief executive, Scott Thompson, came as Facebook moves toward an initial public offering of stock this year that could value the company at $100 billion. 
 
 Yahoo's suit follows recent ...
– Yahoo followed through on its threat to sue Facebook today, filing a suit accusing the social networking company of violating 10 Yahoo patents. The suit, filed by new CEO Scott Thompson, reportedly comes after months of talks between the two companies; it alleges that Facebook got a "free ride" by using patented technology covering everything from messaging to online ads. Yahoo is struggling and Facebook is about to go public; suits like this are common in such cases, an expert tells the Wall Street Journal. Another tells Reuters that the timing might make Facebook "more willing to resolve" the differences. The suit alleges that Facebook succeeded by using principles "Yahoo had its pulse on" years earlier, a former Yahoo exec says; one example is Facebook's newsfeed, which is similar to Yahoo's patent for custom data streams. "With this lawsuit Yahoo is saying they had the ideas first," the exec says. Indeed, the lawsuit quotes Mark Zuckerberg himself, Mashable reports; he once said, "Getting there first is not what it's all about." A Facebook spokesperson says the company first learned of the suit through the media.