Mark Zuckerberg, with an estimated net worth of $6.9 billion, can certainly afford all the bulky hoodies his heart desires. This has been a wardrobe staple for the entrepreneur at least since college, when he wore them through late-night programming binges. The Social Network begins with Zuckerberg in a Gap hoodie, taken from a real photo of the Facebook founder that costume director Jacqueline West found…on Facebook. AP Photo; Merrick Morton These are the most important item in the young Zuckerberg's wardrobe. He has been quoted as saying he wanted to start his own company so no boss could ever tell him not to wear flip-flops to work. Mission accomplished! Until recently, when Zuckerberg began wearing more sneakers and fewer sandals, he was rarely seen outside the house in anything other than these Adidas shoes, which he mostly wore barefoot but occasionally paired with tube socks. AP Photo; Merrick Morton It's so warm and cozy, you never have to take it off—and sometimes Zuckerberg didn't for days on end. One vital element of geek-chic style is a blatant disregard for the conventions of fashion. You wear what you want, when you want, without regard to occasion or trends. If you're Mark Zuckerberg and you want to wear a North Face fleece on stage at a major technology conference (as pictured here), no one's going to complain. Getty Images; Merrick Morton Who has time for hair products when you're busy winning "friends" and alienating everyone? Zuckerberg's trademark kinky 'do, untamed by gel or mousse, has become an enduring element of his style. Also pictured here, at right, is a curious sartorial choice depicted in the film: Zuckerberg layers a lavender T-shirt over a white button-front shirt for a hearing at one of two lawsuits. Newscom; Merrick Morton Nothing says "I could buy this town" like a T-shirt and jeans, worn at all times, without regard to the latest fashions. Zuckerberg wouldn't be caught dead in a pair of $300 Japanese denims from Barneys, and that sort of devil-may-care styling is what helps him stand out—and above—the pack. Where the bankers of the Wall Street era poured their riches into designer duds, Zuckerberg prefers a more Spartan wardrobe. Newscom; Merrick Morton There's really no situation in a young billionaire's life for which a gray T-shirt won't get the job done, clothing-wise. Perfect for afternoon strolls with your girlfriend or meetings with the nation's top venture capitalists, the gray T-shirt really is the "little black dress" of the new elite—a vital wardrobe staple and ideal for all occasions. AP Photo; Merrick Morton Ditto the white button-front shirt, which can be paired with jeans or cargo shorts, sandals or sneakers, under or over a solid-color T-shirt. This look typifies the functionality and utter disregard for trends that are the highlights of Zuckerberg's style. "The wonderful thing about Mark is he looks like he doesn't care at all what he wears, but in a funny way he's created a fashion," said Social Network costume director Jacqueline West. Sipa; Merrick Morton