Sina (Chinese: 新浪; pinyin: Xīn Làng) is a Chinese telecom company. Sina operates four major business lines: Sina Weibo, Sina Mobile, Sina Online, and Sinanet. Sina has over 100 million registered users worldwide. Sina was recognized by Southern Weekend as the "China's Media of the Year" in 2003.

Sina owns Sina Weibo, a Tencent Weibo-like microblog social network, which has 56.5 percent of the Chinese microblogging market based on active users and 86.6 percent based on browsing time over Chinese competitors such as Tencent and Baidu. The social networking service has more than 500 million users and millions of posts per day, and is adding 20 million new users per month, says the company. The top 100 users now have over 180 million followers combined.

It is the largest Chinese-language mobile portal. It is run by Sina Corporation, which was founded in 1999. The company was founded in Beijing, and its global financial headquarters have been based in Shanghai since October 1, 2001.

Sina App Engine (SAE) is the earliest and largest PaaS platform for cloud computing in China. It is run by SAE Department, which was founded in 2009. SAE is dedicated in providing stable, effective web deployment and hosting service for those corporations, organizations and independent developers. Now more than 300,000 developers in China are using SAE.

It mainly caters to the Chinese population around the globe, Sina stated that it has about 94.8 million registered users and more than 10 million active users engaged in their fee-based services (10,000 of whom are overseas Chinese in North America). It provides different services around the world, for example there are 13 access points within Greater China, and subsidiary tailored pages for overseas Chinese, which include Sina US, Sina Japan, Sina Korea, Sina Australia, Sina Europe and Sina Germany.

It is one of the four major business lines of Sina Corporation (NASDAQ: SINA). The rest of the major business lines are Sina Mobile, Sina Online and Sinanet.

The domain sina.com.cn attracted at least 3.3 million visitors annually by 2008 according to a Compete.com survey.

Sina Corp also owns Sina Weibo, a Chinese microblogging site, similar to Tencent Weibo, launched in August 2009. According to Sina Corp the microblogging site has more than 200 million users and millions of posts per day, and is adding 20 million new users per month. The company also said it now has more than 60,000 verified accounts, consisting of celebrities, sports stars and other VIPs. The top 100 users now have over 180 million followers. Furthermore, Sina said that more than 5,000 companies and 2,700 media organizations in China are currently using Sina Weibo.

More recently, Sina also released a "lite-blogging service" similar to Tumblr, called Sina Qing, as well as a location-based service, WeiLingDi.

In a survey conducted by Gallup (China) Research Ltd in April 2003, Sina was the most popular company in China, and was estimated to have three billion page data volumes every day. Also, it was awarded the "China's Media of the Year" in 2003 by Southern Weekend.

(Information based on Xin, 2002)

In March 1999, Stone Rich Sight Information Technology Ltd (四通利方信息技術有限公司, SRS), established by Sina former CEO and President Wang Zhidong (王志東; Wáng Zhìdōng), merged with Sinanet (華渊資訊公司), a US website company of Sunnyvale, California. The merging of the two largest Chinese websites formed into the later Sina. Since then the service had been extended across the straits and North America, before it extended to Hong Kong in July 1999.

Sina overtook the dominant role of sohu for the first time in 1999 by its fast, continuous, and comprehensive reports on the NATO Bombing of the Chinese embassy in Belgrade in 1999, according to CNNIC's survey conducted 2 months after the incident.

Sina was the first to be approved for listing on the Nasdaq National market on 13 April 2000, followed by Netease and Sohu, two other web-based companies in China, in June and July respectively. It succeeded in raising US$68,000,000 before Nasdaq plummeted in May 2000. In July 2000, Sina was the official website for on-line coverage of the 2000 Summer Olympics in Sydney as selected by the government and the Chinese Olympic committee. (Xin, 2002).

Sina cooperates with other web-based companies such as People, Nanfang Daily, Lifeweek and Xinhuanet, etc. Apart from the media partners, its clients include Microsoft, DELL, IBM, Motorola, and Kodak. Recently Sina started developing its business in the field of wireless internet, in the meantime collaborating with China Mobile, China Telecom, Ericsson.

On January 13, 2004, Sina and Yahoo started to jointly provide online auction services in China; in response to this, EachNet (Chinese: "易趣網"), which cooperates with eBay, lowered its registration fee in early February 2004 in order to keep its market share.

Sina also sponsors the annual ChinICT conference held at the Tsinghua Science Park.

Recently, Sina has begun collaborating with Qihoo 360 on internet security. Through this collaboration, Qihoo 360 intend to provide Sina Weibo tech support in order to protect Weibo from hackers and viruses. As of April 24, 2012 an official statement has not yet been made announcing the collaboration.

To provide tailored internet services for local people, Sina has been conducting quantitative and qualitative marketing researches, including demographic research, psychograph, etc., on target audience in specific regions.

Sina provides internet services to the Chinese population around the world. In every localized website, there are over thirty integrated channels, including news, sports, technology information, finance, advertising services, entertainment, fashion, and travel.

Sina is a multiple-service provider, its major services are SMS, Mail, Search, Games, Match, Entertainment, Sina Sports, Sina Blog, and Sina Microblogging. Sina Blog (中文: 新浪博客) is the blog service of Sina, which features the blogs of celebrities, including the most popular blog in the world, the one of Xu Jinglei. Sina Weibo is an equivalent to Tencent Weibo. Many celebrities from mainland China, Taiwan and also Hong Kong use Sina's Microblog as a platform to reach out to their fans and supporters. Some famous users on Sina's Microblog include Taiwanese hosts Dee Shu and Kevin Tsai, with more than ten million followers on their microblogs each.

A big challenge for Sina is monetizing the massive Weibo following. Sina has taken several steps in that direction, and is reportedly developing a "pay-for-forward" feature. The feature will enable users to pay to have a message forwarded by an account with a large following. Sina plans to keep 20% of the revenue generated from "pay-for-forward" fees.

Internationalized services have a common layout which consists of sections like news, information, infotainment and email services with localized content.}

Localization involves political censorship. As with all internet content providers operating within mainland China, the web pages which are geared toward mainland China audiences have internet censors controlling the discussion for sensitive political content. In addition, the news from sina comes from local newspapers, which in the case of mainland China are themselves subject to censorship by the government. This censorship does not extend to pages and forums which are not intended for audiences within mainland China.

Sina provides a lot of feature news and ads as the focus of the lead story or the main photo. On the other hand, its domestic political news is sourced from The People’s Daily or Xinhua News Agency. Compared to conventional medium for news distribution, Sina is a telecom platform for ads from the traditional media. That means, according to its CEO, Wang Zhidong, Sina would never hire journalists (Xin, 2000).

According to the company's published information, Sina.comXpressTM and Sina.comPlusTM are Sina.com's two main exclusive technologies, which bring ease-of-use benefits and enable the audience of Big 5 (traditional Chinese character), and GB (simplified Chinese characters) to view the webpages sourced from around the Chinese communities of the world.