Personal Data's Value? Facebook Is Set to Find Out Robert Galbraith/Reuters An employee at Facebook's headquarters in Menlo Park, Calif. The company, founded in 2004, now has some 800 million users. Facebook, the vast online social network, is poised to file for a public stock offering on Wednesday that will ultimately value the company at $75 billion to $100 billion, cashing in on the fuel that powers the engine of Internet commerce: personal data. A global operations area at the Menlo Park headquarters. The company has been busily collecting that data for seven years, compiling the information that its more than 800 million users freely share about themselves and their desires. Facebook's value will be determined by whether it can leverage this commodity to attract advertisers, and how deftly the company can handle privacy concerns raised by its users and government regulators worldwide. As the biggest offering of a social networking company, the sale is the clearest evidence yet that investors believe there is a lot of money to be made from the social Web. Facebook's dominance in this field has left Google, a Web king from an earlier era - less than a decade ago - racing to catch up. Facebook is considered so valuable because it is more than the sum of its users. More than the world's largest social network, it is a fast-churning data machine that captures and processes every click and interaction on its platform. Every time a person shares a link, listens to a song, clicks on one of Facebook's ubiquitous "like" buttons, or changes a relationship status to "engaged," a morsel of data is added to Facebook's vast library. It is a siren to advertisers hoping to leverage that information to match their ads with the right audience. Barring an unforeseen event, the Internet giant plans to list a preliminary fund-raising goal of $5 billion, according to people briefed on the matter, smaller than some previous estimates of the offering. But it is essentially a placeholder, a starting point used by companies to generate interest among potential investors. The eventual offering is expected to be the largest for an Internet company, bigger than Google's in 2004 or Netscape's nearly a decade before that. Trading of the stock is expected to begin by late May, the people briefed on the matter said. The offering will compel Mark Zuckerberg, Facebook's 27-year-old founder and chief executive, to do what he has until now preferred to avoid: share information about his company. Facebook, created in 2004 in Mr. Zuckerberg's dorm room at Harvard, grew from being a quirky site for college students into a remarkably popular platform that is used to sell cars and movies, win over voters in presidential elections and organize protest movements. It jumped from 50 million users in 2007 to 800 million in 2011, according to company figures. It offers advertisers a global platform, with three-fourths of its users outside the United States; the notable exception is China, where Facebook does not operate. Facebook's offering is "an American milestone," said Lawrence H. Summers, the former Treasury secretary, who has been a mentor to Sheryl Sandberg, Facebook's chief operating officer, and knows Mr. Zuckerberg. Many companies provide products that let people do things they've done before in better ways. Most important companies, like Ford in its day or I.B.M. in its, are those that open up whole new capabilities and permit whole new connections. Facebook is such a company. Facebook has deftly kept more and more users on its site for hours every day. Its users can stream music, read the news, play virtual games, check horoscopes or upload family pictures - all without leaving Facebook's orbit. They reveal to the company not only their names (Facebook prohibits pseudonyms) and hometowns, but also their friends and family members and their tastes on everything from pop music to politics. Facebook offers advertisers a giant basket of information so they can find precisely the audience they covet: a Boston woman who posts that she is "engaged" may be offered an ad for a wedding photographer on her Facebook page, while a Bombay bride-to-be might see ads for wedding saris. Similarly, every press of a "like" button on Facebook signals a consumer's preferences and shapes the ads that are shown. The Facebook Connect service allows users to log into millions of sites using their Facebook username and password - and it can report back about their activity on those sites, amassing even more data for Facebook's trove. Michael J. de la Merced contributed reporting.