In February 2011, Tom Cruise tweeted to his followers on Twitter: “We’re having fun talking to you & our new friends at http://t.sina.com.cn/. It’s the Chinese Twitter, but with a lot more functionality.” The fun he was having with his new, superior Twitter delighted China, since it was evidence that Weibo (which translates from Chinese literally as “microblog”) is the belle of the global microblogging ball. Cruise wrote in his giddy inaugural “weibos”: “It’s exciting to be here with you. We look forward to learning more about Weibo” and “Hello! We have some questions about adding a background and posting etiquette. Is this where we should ask? Thank you!” Thousands of eager fans offered instant advice, including: “I can teach you Chinese if you come to Shanghai,” and “Dear Mr. Cruise, As for posting etiquette, I don’t think you should have to worry about that. As long as you don’t post anything offensive religiously, politically, culturally :) Welcome to Weibo.”

To his now 3.2 million Weibo followers, Cruise is known as “Tom Brother.” And Tom Brother is not the only Western star with love to show the East; British actress Emma Watson wrote her first Weibo post on July 8, 2011: “Hi everyone, this is the Real Me ( @ EmWatson )! Very excited about my new Weibo page”; N.B.A. star Kevin Durant “weiboed”: “I love China, cannot wait to go there again”; President Bush’s brother Neil joined in with: “In the past 35 years, I have been to China 80 times and am in awe of China’s development.” And Radiohead, in spite of the band’s history of criticizing the Chinese government, arrived with a shy first post: “testing the weibo . . . ”

“It’s like ET,” says Cai Jinqing, a Beijinger with more than 120,000 followers. She imitates a foreigner arriving on Weibo by putting her hands in the air and then landing them in front of her in a gesture of fresh arrival and tremendous confusion. “I’m going to touch down into this world and see what it’s like!” Because the Chinese find Western curiosity and friendliness endearing, they celebrate posts like Cruise’s early ones for what Cai calls “willingness to show vulnerability” or “authenticity.” “Especially if you’re famous,” Cai says, “you have to loosen up your language. You have to show China your real self.”

The Chinese social-networking scene is crowded with microblogging sites for China’s 500 million Internet users. Sina Weibo, launched in August 2009 as an accessory to Sina, one of China’s most established portals, is the fastest growing and most talked about, home to more than 250 million users and growing at a rate of about 10 million a month.

Sina is listed on nasdaq. But since the Chinese government restricts foreign direct investment in certain sectors, Sina uses a variable interest entity (v.i.e.) to filter capital through a Cayman Islands bridge company and a chain of intermediaries. The founders in China sort of own it; the investors in New York sort of own it. Sina is run by Charles Chao, a Chinese-born, American-educated journalist and accountant who joined Sina in 1999 as a V.P. of finance and rose through the ranks to become C.E.O. in 2006. In other words, Sina is a perfect example of 21st-century global capitalism; it’s both public and private, local and international, American and Chinese.

The site’s dominance owes a great deal to its courtship of celebrity users; Sina focused on gathering and “verifying” stars, and fans flocked to the site. (It’s a strategy that Western newcomers to the microblogging/social-networking business, like Google+, have attempted in various ways, and with varying degrees of success). Sina Weibo verifies the authenticity of celebrities’ identities by putting a gilded V next to the profiles of public people who meet the requirements for verification—that is, who can prove they’re who they say they are. The rest of us end up relegated to slightly inferior status, with commoner accounts. This two-tier system of verification may seem ironic in a society (and on a microblog platform) that purports to promote social equality, but it both reflects and begets a powerful desire for “authenticity” on the site and in Chinese culture generally. Verification suggests the possibility of distinguishing - on Weibo and beyond - between true and false, original and mimicked, real and fake.