Don\'t try to friend MaLi Arwood on Facebook. You won\'t find her there. You won\'t find Thomas Chin, either. Or Kariann Goldschmitt. Or Jake Edelstein. More than 900 million people worldwide check their Facebook accounts at least once a month, but millions more are Facebook holdouts. They say they don\'t want Facebook. They insist they don\'t need Facebook. They say they\'re living life just fine without the long-forgotten acquaintances that the world\'s largest social network sometimes resurrects. They are the resisters. \"I\'m absolutely in touch with everyone in my life that I want to be in touch with,\" Arwood says. \"I don\'t need to share triviality with someone that I might have known for six months 12 years ago.\" Even without people like Arwood, Facebook is one of the biggest business success stories in history. The site had 1 million users by the end of 2004, the year Mark Zuckerberg started it in his Harvard dorm room. Two years later, it had 12 million. Facebook had 500 million by summer 2010 and 901 million as of March 31, according to the company. That staggering rise in popularity is one reason why Facebook Inc.\'s initial public offering is one of the most hotly anticipated in years. The company\'s shares are expected to begin trading on the Nasdaq Stock Market on Friday under the ticker symbol \"FB\". Facebook is likely to have an estimated market valuation of some $100 billion, making it worth more than Kraft Foods, Ford or Disney. Facebook still has plenty of room to grow, particularly in developing countries where people are only starting to get Internet access. As it is, about 80 percent of its users are outside U.S. and Canada. But if Facebook is to live up to its pre-IPO hype and reward the investors who are clamoring for its stock this week, it needs to convince some of the resisters to join. Two out of every five American adults have not joined Facebook, according to a recent Associated Press-CNBC poll. Among those who are not on Facebook, a third cited a lack of interest or need. If all those people continue to shun Facebook, the social network could become akin to a postal system that only delivers mail to houses on one side of the street. The system isn\'t as useful, and people aren\'t apt to spend as much time with it. That means fewer opportunities for Facebook to sell ads. Lee Rainie, director of the Pew Internet & American Life Project, says that new communications channels _ from the telephone to radio, TV and personal computers - often breed a cadre of holdouts in their early days. \"It\'s disorienting because people have different relationships with others depending on the media they use,\" Rainie says. \"But we\'ve been through this before. As each new communications media comes to prominence, there is a period of adoption.\"