Li Yufei, an 18-year-old student at Shanghai Maritime University, finds Korean television shows online, plays video games and has 300 Web buddies.

“I started doing a lot of this when I was about 11 years old,” says Mr. Li, a freshman at the Shanghai Maritime University. “Now, I spend most of my leisure time on the Internet,” he says. “There’s nowhere else to go.”

Google’s decision last month to remove some of its operations from China has overshadowed a startling dynamic at work in this country, a place where young people complain that there is not a lot to do: the Internet, already a potent social force here, has become the country’s prime entertainment service.

Frustrated with media censorship, bland programming on state-run television and limits on the number of foreign films allowed to be shown in China each year, young people are logging onto the Web and downloading alternatives. Homegrown Web sites like Baidu, Tencent and Sina.com have captured millions of Chinese youths obsessed with online games, pirated movies and music, the raising of virtual vegetables, microblogging and instant messaging.

Even though Facebook, Twitter and YouTube are blocked by censors here, Chinese social networking sites like QQ Zone, Tianya.cn and Kaixin001.com are flourishing in surprisingly inventive ways.

A study conducted by the Boston Consulting Group found that people in China (which now has nearly 400 million Internet users) are far more connected than Americans, and that globally only the Japanese spend more time on the Web.

The surprising power of online communities in China has Communist Party leaders worried about the ability of online social networks to spread viral messages that could ignite social movements, and pose a challenge to the party and its leaders. They saw what happened to Han Feng, a midlevel party official in southern China, when his private diary was recently posted online.

In the diary, Mr. Han catalogued not just the hefty bribes he was taking, but detailed his sexual escapades with co-workers and mistresses. The ensuing online uproar led to his sacking and a criminal investigation.

But young people in China say they are excited about the Web not because it offers a means to rebellion, but because it gives them a wide variety of social and entertainment options.

One of the more remarkable developments in the Internet in recent years has been the informal network of young people who volunteer to produce Chinese subtitles for popular American television series like “Prison Break” and “Gossip Girl.”

The Chinese subtitles are often translated within hours of the program’s showing in the United States, and then attached to the video and made freely available on Chinese file-sharing sites.

Chinese Internet companies have gleaned a lesson from this: entertainment trumps politics on the Web in China.

“The Web is really a reflection of real life,” says Gary Wang, founder and chief executive of Tudou, one of China’s biggest video-sharing sites. “What people do in real life is they go to karaoke rooms, they go to bars, they get together with friends and they shop. And that’s what they do online.”

By the time Google sold its stake in Baidu and set up its own Chinese-language search engine in 2006, Baidu was already expanding its site in the hopes of building a community that would stick around longer on the site.

One of the company’s most popular offerings is the Baidu Post Bar, an online bulletin board of hot topics that now accounts for nearly 15 percent of the site’s traffic. (Among the most popular topics in recent weeks was a television anchorwoman’s ties to a corrupt official).

There is also Baidu Knows, Baidu Space (for blogs) and Baidu Baike, a Chinese version of Wikipedia.

Just like American TV networks, state-run networks in China are worried that entertainment is migrating to the Web and that young people are souring on television. So they are trying to jazz up their offerings with reality shows or programs modeled on “American Idol.”

Sometimes, though, network news divisions get even by investigating the follies of their Web competitors.

In 2008, for instance, China Central Television — the biggest state-run network — ran an exposé on how Baidu accepted money to bolster the search results of unlicensed medical companies.

Baidu reviewed its policies, but also cleverly managed its way through the scandal by paying more than $5 million to be a sponsor of the state network and by courting the Chinese press.

Several Chinese journalists say that soon after Baidu suffered bad publicity, the company offered to fly a group of journalists to Hong Kong for a leisurely weekend at a luxury hotel.

A spokeswoman for Baidu declined to comment on the Hong Kong press outing, but media coverage of Baidu improved.

Analysts say Microsoft’s new search engine, Bing, also has little chance of succeeding. Although Microsoft has spent years building a presence in China and working with the Chinese government, the company’s online offerings have fared poorly.

“I don’t think Bing will come even close to Baidu,” said Lu Bowang, president of China IntelliConsulting in Beijing. A Microsoft spokesman declined to comment on Bing’s China strategy.

Mr. Li, the Shanghai Maritime University student, says he surfs the Web to find or build his own community. A shy person with no siblings, he now has 300 online buddies, and says he turns to the Web to find what he cannot find anywhere else, particularly on state-run TV, which banned some Korean shows years ago.

“The State Administration shut down a lot of the popular Japanese and Korean series a long time ago,” he says. “So I have to go online to find things like this.”