The People's Republic of China (PRC) has the world's largest number of Internet users, estimated at 500 million people, including an estimated 300 million people with accounts on Twitter-like microblogging sites. Despite government efforts to limit the flow of information, Chinese Internet users are able to access unprecedented amounts of information, and the web has served as a lifeline for political dissidents, social activists, and civil society actors. "Netizens" have helped to curb some abuses of government authority and compelled some officials to conduct affairs more openly. The web also has enabled the public to engage in civil discourse on a national level. Some government departments have begun to solicit online public input on policy issues. However, the Internet has proven to be less of a catalyst for democratic change in China than many foreign observers had initially expected or hoped. Along with its extensive internal security apparatus, China also has an aggressive and multi-faceted Internet censorship system. In 2011, Freedom House ranked China as one of the five countries with the lowest levels of Internet and "new media" freedom. According to some estimates, roughly 70 Chinese citizens are serving prison sentences for writing about politically sensitive topics online. The development of the Internet and its use in China have raised U.S. congressional concerns, including those related to human rights, trade and investment, and cybersecurity. Congressional interest in the Internet in China is linked to human rights in a number of ways. These include the use of the Internet as a U.S. policy tool for promoting freedom of expression and other rights in China; the use of the Internet by political dissidents in the PRC and the political repression that such use often provokes; and the role of U.S. Internet companies in both spreading freedom in China and cooperating with PRC censorship and social control efforts. In addition to the effectiveness of censorship, some studies show that the vast majority of Internet users in China do not engage the medium for political purposes. Although a small community of dissidents and activists use the web to broach political topics, they reportedly make up a small minority—less than 10% of all users according to some estimates. Between 1% and 8% of web users in China use proxy servers and virtual private networks to get around government-erected Internet firewalls to access censored content—both political and non-political. The widespread satisfaction reportedly felt by many Chinese Internet users has reduced public pressure for greater freedom. Although netizens have frequently protested against government actions aimed at further controlling web content and use, the Internet in China offers a wide and attractive range of services, making restrictions almost unnoticeable to many users. Furthermore, some experts argue that the Internet in China has created an illusion of democracy by allowing people to vent their opinions online and by providing venues for debate on some political and policy issues. Moreover, many Chinese accept the government's justification that it regulates the Internet in order to control illegal, harmful, or dangerous online content, services, and activities, such as pornography, gambling, slander, cyberattacks, and social networking by criminal organizations. U.S. efforts to promote Internet freedom have broadened. Since the early 2000s, policy makers have focused on supporting censorship circumvention techniques and their use in China, protecting the privacy of Chinese Internet users, and discouraging or preventing U.S. information and communications technology companies from aiding Beijing's censorship efforts and public surveillance system. According to some analysts, counter-censorship technology has proven to have a vital, but limited, impact on the promotion of freedom and democracy in the PRC. They have advocated a broader approach or the development of a more comprehensive and robust mix of tools and education for "cyber dissidents" and online activists in China and elsewhere, including the following: software and training to help dissidents and civil society actors communicate securely through evading surveillance, detecting spyware, and guarding against cyberattacks; archiving and disseminating information that censors have removed from the Internet; developing means of maintaining Internet access when the government has shut it down entirely; and providing training in online communication, organization, and advocacy. The PRC government employs a variety of methods to control online content and expression, including website or IP address blocking and keyword filtering by routers at the country's eight Internet "gateways," telecommunications company data centers, and Internet portals; regulating and monitoring Internet service providers, Internet cafes, and university bulletin board systems; registering websites and blogs; and occasional arrests of high-profile "cyber dissidents" or crackdowns on Internet service providers. Some analysts argue that even though the PRC government cannot control all Internet content and use, its selective targeting creates an undercurrent of fear and promotes self-censorship. Blocked websites, social networking sites, and file sharing sites include Radio Free Asia, Voice of America (Chinese language), international human rights websites, many Taiwanese news sites, Facebook, Twitter, and YouTube. Online English language news sites, including the Voice of America, the New York Times , and the Washington Post , are generally accessible or only occasionally or selectively censored. Commonly barred Internet searches and microblog postings include those with direct and indirect or disguised references to Tibet; the Tiananmen suppression of 1989; Falun Gong; PRC leaders and dissidents who have been involved in recent, politically sensitive events; democracy; highly charged foreign affairs issues; and sexual material. The government reportedly also has hired thousands of students to express pro-government views on websites, bulletin boards, and chat rooms. Some experts argue that China's success in maintaining control over the Internet is based largely upon its reliance on private sector actors and profit motives. By imposing non-coercive incentives for compliance, the government has been able to maintain a fairly reliable system of control at relatively little cost. In order to maintain their business licenses and operate in China, domestic and foreign Internet companies are required to abide by a rough set of guidelines issued by central and local government agencies—and thus encouraged to practice self-censorship. Companies that have learned how to prosper in this environment include Baidu, China's largest search engine, Sina Weibo, which offers a Twitter-like microblogging platform, and Tencent, which provides instant messaging services. Large Internet portals are estimated to each employ hundreds of people to filter online discussion. Sina Weibo is said to employ approximately 1,000 people to monitor and censor expression on its social networking service. In May 2012, Sina instituted a point system in which customers are given a number of starting points that are deducted if they post "harmful" content. If a customer's cache of points falls to zero, then his or her account is terminated. Service providers are often torn between providing interesting content and allowing wide-ranging discussion, on the one hand, and complying with government guidelines, on the other, both of which can affect their economic survival. Another aspect of the PRC government's ability to control online information is the degree to which the experience of the Internet user in China resembles that of Internet users in freer environments elsewhere. The abundant array of offerings on China's Internet, vibrant news coverage, public discourse on a range of issues, and selective rather than widespread use of coercive measures, such as arrests of netizens who use the Internet for political purposes, has diluted opposition to China's censorship regime. Although their foreign counterparts are blocked, Chinese can search terms on Baidu, engage in social networking on RenRen and Kaixinwang, and blog or "Tweet" via Sohu and Sina platforms. These phenomena have even been referred to by Chinese officials as "Internet democracy." One U.S. expert states that "China's 500 million Internet users feel free and are less fearful of their government than in the past. The communications revolution has transformed China in many ways, but the Communist Party has thus far succeeded—against all odds and expectations—in controlling it to remain in power." Since Internet use became widespread in China in the mid-2000s, the government and netizens have engaged in a game of cat and mouse, with new communications platforms challenging the government's efforts to control the web, followed by crackdowns or new regulations, and then a repeat of the cycle. Bulletin and message boards, personal websites, blogs, microblogs, and other communication outlets have allowed for an unprecedented amount of information and public comment on social and other issues. Although the state has the capability to block the dissemination of news or shut down the Internet, as it did in Xinjiang for several months following the social unrest that erupted there in July 2009, it often cannot do so before such events are publicized, if only fleetingly, online. For Chinese Internet users in search of blocked information from outside the PRC's Internet gateways, or "great firewall," circumventing government controls (also known as fanqiang or "scaling the wall") is made possible by downloading special software. These methods mainly include proxy servers, which are free but somewhat cumbersome, and virtual private networks (VPNs), which are available at a small cost (roughly $40.00) but also enable secure communication. Proxy servers and VPNs enable some motivated Internet users to avoid censorship, but impose just enough inconvenience to keep foreign information out of the reach of most Chinese users. The use of these tools is tolerated by the government as long as it remains politically manageable, according to some observers. However, the government occasionally has attempted to curtail their use, as in 2011, when users of VPNs began to experience interference with their access to foreign websites. While remaining vigilant against Internet activities that it perceives may give rise to organized or potentially destabilizing political activities, the PRC government has been careful not to unnecessarily provoke the ire of the general online population. Nor does it want to alienate China's international business community, which relies upon Internet services as well as VPNs.