Tony Hsieh founded the shopping Web site Zappos.com, which was sold to Amazon.com for more than $1 billion. Isaac Brekken for The New York Times

HENDERSON, Nevada - Tony Hsieh, the chief executive of Zappos.com, is not yet a household name, even among the legions of customers who delight in Zappos's large selection of shoes and clothes, free shipping and free returns. But he has become a celebrity in entrepreneurial circles.

Mr. Hsieh, 37, sold his first company, LinkExchange, to Microsoft for $265 million when he was just 24, then turned Zappos into the largest seller of shoes online. In 2009, he sold Zappos to Amazon.com for more than $1 billion, though he continues to run the company.

His profile is growing. His book, "Delivering Happiness: A Path to Profits, Passion and Purpose," spent 27 weeks on the New York Times best-seller list. He was a judge on the TV show "Celebrity Apprentice." And he has 1.8 million followers on Twitter.

With close-cropped black hair and speaking quietly, with little inflection, Mr. Hsieh calls little attention to himself in a group, often lingering on the sidelines.

"He draws energy from people," said Alfred Lin, a Harvard University classmate of Mr. Hsieh's who was Zappos's chief financial officer until last year. "But he's not an overtly 'Hey, I'm the center of the party' kind of guy."

And yet, like Facebook's Mark Zuckerberg, Mr. Hsieh has built his success in part on his ability to anatomize the way people crave connections with others.

He has never pretended to be interested in shoes. But by promoting the perks of a highly social company where workers get free sodas and popcorn, decorate their cubicles, are invited to share their ideas and can climb the career ladder from inside, Zappos is able to pay below market salaries for its more senior workers.

"We want them to work for us for reasons other than money," Mr. Hsieh said with a shrug.

Recruiters boast that it is harder to get a job at Zappos than to get admitted to Harvard.

Although his admirers credit Mr. Hsieh with having created a unique culture at Zappos, others point out that what he is doing is actually simple, and perhaps not so original. Nick Swinmurn, the Zappos founder, who left the company in 2006, said: "If you take away the culture and keep the free shipping and the free returns, it's the selection and the free shipping that keep the company growing."

At times, Mr. Hsieh comes across as a watchful alien. "I have been in job interviews with him where you are expecting more, and it can be awkward silences," said Ned Farra, who manages relationships with other Web sites for Zappos.

Mr. Hsieh said that he likes people who are more outgoing than he is. "My view is that I am more of a mirror of who I am around," he said. "So if I am around an introverted person that is really awkward."

Mr. Hsieh has "a form of social phobia," said Antonia Dodge, a "personality assessment consultant" to Zappos. "But he gallantly walks over it by not letting it stop him and always pursues social situations. And second, he lubricates with tons of vodka."

For all Mr. Hsieh's emphasis on the importance of relationships, his romantic life remains a mystery. Close friends and employees either giggled nervously or balked outright at queries about it.

At a quarterly awards party for employees, Mr. Hsieh gamely joined in the karaoke singing. The employees talked affectionately about him after he had quietly slipped out. "Sometimes I look at him, and I say, 'He is such a dork,'" said Lauren Glassman, a buyer in the action sports clothing division. "But at the end of the day, we are all dorks."

The New York Times