Baidu, Inc. (Chinese: 百度; pinyin: Bǎidù, anglicized /ˈbaɪduː/ "BY-doo"), incorporated on 18 January 2000, is a Chinese web services company headquartered at the Baidu Campus in Beijing's Haidian District. It is one of the largest internet companies, and one of the premier AI leaders in the world. The holding company of the group was incorporated in the Cayman Islands. Baidu was established in 2000 by Robin Li and Eric Xu. Both of the co-founders are Chinese nationals who studied in Peking University and worked overseas before returning to China. In December 2016, Baidu ranked 4th overall in the Alexa Internet rankings.

Baidu's Global Business Unit, formed under the name of DU Group or DU Apps Studio, is an app developer with a wide variety of popular award-winning apps and services, accumulating over 2 billion users worldwide. It aims to provide innovative products, as well as new and exciting business models and ways to interact with technology, through AI and mobile devices. It has also established offices around the world including Brazil, India, Indonesia, Thailand, Egypt, Japan and the United States, with the goal of becoming the core player in shaping how technology works, in every continent. Its award-winning products include DU Battery Saver, DU Speed Booster, MoboMarket, DU Browser, Facemoji Keyboard, DU Flashlight, DU Security, DU Cleaner, DU Privacy Vault, DU Antivirus, Photo Wonder, DU Caller, DU Recorder, ES File Explorer, Simeji, and more. Baidu also provides an official international and Chinese version of its widely popular online digital distribution services Baidu App Store and Shouji Baidu respectively, both hosting vast amount of downloadable content and applications from all over the world.

Baidu has the 2nd largest search engine in the world, and held a 76.05% market share in China's search engines market, the largest in the world, as of April 2017. In December 2007, Baidu became the first Chinese company to be included in the NASDAQ-100 index.

As of 2017, Baidu Search released Spider 3.0 which is capable of indexing over trillions of web pages. Baidu offers multimedia content including MP3 music, and movies, and is the first in China to offer Wireless Application Protocol (WAP) and personal digital assistant (PDA)-based mobile search.

Baidu Brain, the company's AI-based artificial neural network has achieved a remarkable 97% accuracy rate in voice recognition and 99.7% rate in facial recognition, confirming the success of its AI development.

Baidu Cloud, the company's cloud arm has received recognition from many industries due to its unique offerings, it adopts an integrated approach that combines capabilities and resources in AI, Big Data and Cloud Computing, providing customers with not only storage and computing but also complete solutions and services that are ready to deploy. Numerous companies and organisations have been using Baidu Cloud to increase the accuracy and efficiency of their products and services, as well as developing new technologies. The customer base of Baidu Cloud has increased 10 folds year-over-year, with traffic increasing eight folds and revenue increasing four folds. Recently, it has released the ABC – STACK, a hybrid cloud platform that provides enterprise customers with powerful and flexible solutions to effectively integrate and deploy AI into their businesses.

Baidu Baike is similar to Wikipedia as an online encyclopedia; however, unlike Wikipedia, only registered users can edit the articles due to Chinese laws. While access to Wikipedia has been intermittently blocked or certain articles filtered in China since June 2004, there is some controversy about the degree to which Baidu cooperates with Chinese government censorship.

The company also hosts a music service Baidu Music that has more than 200 million monthly active users, news service Baidu News Feed that has more than 100 million daily active users, and food delivery service Baidu Waimai that has more than 100 million monthly active users. On 4 December 2015, Baidu announced plans to merge with Taihe Entertainment Group to help the service compete with Apple Inc.'s Apple Music.

In 2017, Baidu announced that its ambitious Apollo autonomous driving program (often called the ‘Android of the autonomous driving industry’, an open source platform for self-driving that includes hardware, software and cloud data services for autonomous vehicles) has over 50 partners (automakers, tier 1 suppliers, component producers, startups, academic institutions, government departments, artificial intelligence and technology companies), including FAW Group, one of the major Chinese carmakers that will work with Baidu on commercialization of the technology. Other partners include worldwide auto companies Chery, Volkswagen, General Motors, Hyundai, Daimler AG (Mercedes-Benz), BYD, Ford, Changan Automobile, ZF Friedrichshafen, BAIC, JAC and Great Wall Motors, as well as global organisations Tsinghua University, Intel, ZTE, Bosch, Continental AG, Nvidia, Microsoft, Velodyne, NXP Semiconductors, TomTom, UCAR, Grab, AutonomouStuff, Horizon Robotics and more.

By the end of 2020, Baidu hopes to offer a platform that can handle full autonomous driving on both urban roads and highways, and mass-producing its own self driving cars at a later period. It also plans to use its voice interaction and AI operating system DuerOS that already has more than 100 partners (such as Nvidia, Haier, Media, HTC, Vivo, and Harman International), together with the Apollo platform to create the world's largest autonomous driving system with high-precision maps, and setting up Apollo companies around the world. Baidu has recently begun a spree of acquisitions targeting AI and technology start-ups to further advance its AI ambitions, it aims to become the global leader of Artificial Intelligence just as China outlines its plans to achieve global AI leadership by 2030, and to "make DuerOS the most widely used conversational AI platform in the world". Project Apollo has also been praised as "an important milestone for the automotive industry and artificial intelligence". According to a report, Baidu's self-driving AI technology may be valued at nearly US$650 billion and produce a US$120 billion annual revenue for the company by 2021, it will also boost its market cap to over US$1 trillion in the long term.

Its first artificial intelligence (AI) developer conference Baidu Create was held at the China National Convention Center (CNCC) in Beijing on 5 July 2017, it convened Baidu executives and engineers as well as developers and experts across the AI industry. An annual Baidu World technology conference was also announced with its first conference (Bring AI to Life) being held and live-streamed on 16 November 2017 at China World Summit Wing and Kerry Hotel, bringing together Baidu executives, employees, partners, developers, and media to discuss the company’s mission and strategy, technology breakthroughs, new product developments, as well as its open artificial intelligence (AI) ecosystem.

As of October 2017, Baidu's market cap rose to US$94.67 billion, with a recent surge in its stocks, net profit and revenue. It has announced partnership with AMD and will leverage the two companies' world-class technology and software engineering capabilities to create a comprehensive and open ecosystem to address the growing demand for data center workloads and provide more intelligent human-computer interaction, as well as working with JD.com to offer AI-driven advertising and app integration. Baidu has created its own equity fund Baidu Fund Partnership to invest in internet and other technology endeavors, as well as Apollo Fund to invest in future autonomous driving projects. It has also announced plans to create a DuerOS Fund in the future.

In 1994, Robin Li (Li Yanhong, 李彦宏) joined IDD Information Services, a New Jersey division of Dow Jones and Company, where he helped develop software for the online edition of the Wall Street Journal. He also worked on developing better algorithms for search engines and remained at IDD Information Services from May 1994 to June 1997.

In 1996, while at IDD, Li developed the RankDex site-scoring algorithm for search engines results page ranking and received a US patent for the technology. He later used this technology for the Baidu search engine.

In 2000, the company Baidu launched in Beijing, China. The first office was located in a hotel room, which was near Peking University from where Robin graduated.

In 2003, Baidu launched a news search engine and picture search engine, adopting a special identification technology capable of identifying and grouping the articles.

On January 12, 2010, Baidu.com's DNS records in the United States were altered such that browsers to baidu.com were redirected to a website purporting to be the Iranian Cyber Army, thought to be behind the attack on Twitter during the 2009 Iranian election protests, making the proper site unusable for four hours. Internet users were met with a page saying "This site has been attacked by Iranian Cyber Army". Chinese hackers later responded by attacking Iranian websites and leaving messages. Baidu later launched legal action against Register.com for gross negligence after it was revealed that Register.com's technical support staff changed the email address for Baidu.com on the request of an unnamed individual, despite failing security verification procedures. Once the address had been changed, the individual was able to use the forgotten password feature to have Baidu's domain passwords sent directly to them, allowing them to accomplish the domain hijacking.

On August 6, 2012, the BBC reported that three employees of Baidu were arrested on suspicion that they accepted bribes. The bribes were allegedly paid for deleting posts from the forum service. Four people were fired in connection with these arrests.

On July 16, 2013, Baidu announced its intention to purchase 91 Wireless from NetDragon. 91 Wireless is best known for its app store, but it has been reported that the app store faces piracy and other legal issues. On August 14, 2013, Baidu announced that its wholly owned subsidiary Baidu (Hong Kong) Limited has signed a definitive merger agreement to acquire 91 Wireless Web-soft Limited from NetDragon Web-soft Inc. for $1.85 billion in what was reported to be the biggest deal ever in China's IT sector.

On July 31, 2012, Baidu announced they would team up with Sina to provide mobile search results.

On November 18, 2012, Baidu announced that they would be partnering with Qualcomm to offer free cloud storage to Android users with Snapdragon processors.

On August 2, 2013, Baidu launched its Personal Assistant app, designed to help CEOs, managers and the white-collar workers manage their business relationships.

On May 16, 2014, Baidu appointed Dr. Andrew Ng as chief scientist. Dr. Ng will lead Baidu Research in Silicon Valley and Beijing.

On July 18, 2014, the company launched a Brazilian version of the search engine, Baidu Busca.

On October 9, 2014, Baidu announced acquisition of Brazilian local e-commerce site Peixe Urbano.

In April 2017, Baidu announced to launch Apollo project, its self-driving vehicle platform in a bid to help drive the development of autonomous cars including vehicle platform, hardware platform, software platform and cloud data services. Baidu plans to launch this project in July this year, before gradually introducing fully autonomous driving capabilities on highways and open city roads by 2020.

In June 2017, Baidu partnered with Continental and Bosch, auto industry suppliers, on automated driving and connected cars.

In September 2017, Baidu has rolled out a new portable talking translator that can listen and speak in several different languages. Smaller than a typical smartphone, the 140-gram translation device can also be used as a portable Wi-Fi router and is able to operate on networks in 80 countries, it is still under development currently. Baidu will also be inserting artificial intelligence (AI) technology into smartphones, through its deep learning platform. At the same period, it has also led a joint investment of US$12 billion with Alibaba Group, Tencent, JD.com and Didi Chuxing, acquiring 35% of China Unicom's stakes.

In October 2017, According to The Wall Street Journal, Baidu would be launching self-driving bus in China the following year. In the same month, Baidu also announced its first annual Baidu World technology conference (Bring AI to Life) would be held and live-streamed on 16 November 2017 at China World Summit Wing and Kerry Hotel, bringing together Baidu executives, employees, partners, developers, and media to discuss the company’s mission and strategy, technology breakthroughs, new product developments, as well as its open artificial intelligence (AI) ecosystem.

The name Baidu (百度) literally means "a hundred times", or alternatively, "countless times". It is a quote from the last line of Xin Qiji (辛弃疾)'s classical poem "Green Jade Table in The Lantern Festival" (青玉案·元夕) saying: "Having searched thousands of times in the crowd, suddenly turning back, She is there in the dimmest candlelight." (众里寻他千百度 ，蓦然回首，那人却在灯火阑珊处。)

Baidu offers several services to locate information, products and services using Chinese-language search terms, such as, search by Chinese phonetics, advanced search, snapshots, spell checker, stock quotes, news, knows, postbar, images, video and space information, and weather, train and flight schedules and other local information. The user-agent string of Baidu search engine is Baiduspider. Also, a Baidu application for Apple's iOS is available.

Baidu's primary advertising product is called Baidu Tuiguang and is similar to Google Adwords and Adsense. It is a pay per click advertising platform that allows advertisers to have their ads shown in Baidu search results pages and on other websites that are part of Baidu Union.

Baidu sells its advertising products via a network of resellers.

Baidu's web administrative tools are all in Chinese, which makes it tough for non-Chinese speakers to use. Recently, a third-party company began to develop a tool with an English-language interface for Baidu advertising programs.

Moreover, the service may only be used by advertisers with a registered business address in China or in several other East Asian countries.

Baidu focuses on generating revenues primarily from online marketing services. Baidu's pay for placement (P4P) platform enables its customers to reach users who search for information related to their products or services. Customers use automated online tools to create text-based descriptions of their web pages and bid on keywords that trigger the display of their webpage information and link. Baidu's P4P platform features an automated online sign-up process that customers use to activate their accounts at any time. The P4P platform is an online marketplace that introduces Internet search users to customers who bid for priority placement in the search results. Baidu also uses third-party distributors to sell some of its online marketing services to end customers and offers discounts to these distributors in consideration of their services.

Baidu offers certain consultative services, such as keyword suggestions, account management and performance reporting. Baidu suggests synonyms and associated phrases to use as keywords or text in search listings. These suggestions can improve clickthrough rates of the customer's listing and increase the likelihood that a user will enter into a transaction with the customer. Baidu also provides online daily reports of the number of clickthroughs, clicked keywords and the total costs incurred, as well as statistical reports organized by geographic region.

Baidu offers ProTheme services to some of its Baidu Union members, which enable these members to display on their properties its customers' promotional links that are relevant to the subject and content of such members' properties. Baidu generates revenues from ProTheme services based on the number of clicks on its customers' links and share the revenues with its Baidu Union members in accordance with pre-agreed terms. Baidu's fixed-ranking services allow customers to display query-sensitive text links at a designated location on its search results pages. Its Targetizement services enable customers to reach their targeted Internet users by displaying their advertisements only when their targeted Internet users browse Baidu's certain Web pages.

Baidu operates its advertising service, Baidu TV, in partnership with Ads it! Media Corporation, an online advertising agency and technology company. Baidu TV provides advertisers access to the websites of its Baidu Union members, allowing advertisers to choose Websites on which they post their video advertisements with the aid of its advertisement targeting and matching system. It also offers a brand advertising service, Brand-Link. In June 2008, Baidu launched My Marketing Center, a customized platform integrating industry information, market trends and business, and industry news and reports to assist existing customers in their sales and marketing efforts. Other forms of its online advertising services allow customers to display query sensitive and non-query sensitive advertisements on its websites, including graphical advertisements.

Baidu Union consists of several third-party websites and software applications. Union members incorporate a Baidu search box or toolbar and match its sponsored links with the content on their properties. Their users can conduct search via the Baidu search box or toolbar and can click the sponsored links located on their properties. Baidu has also launched programs through which it displays the online advertising of its customers on Baidu Union websites, and share the fees generated by these advertisements with the owners of these Baidu Union websites. As of May 2011, there were 230 thousand partner websites that displayed Baidu Union ads on their websites.

Baidu competes with 360 Search (www.so.com), Sogou Search (www.sogou.com), Yahoo! China, Microsoft's Bing and MSN Messenger, Sina, Wikipedia, NetEase's Youdao, Tencent's Soso.com and PaiPai, Alibaba's Taobao, TOM Online, and EachNet.

Baidu is the No. 1 search engine in China, controlling 63 percent of China's market share as of January 2010, according to iResearch. The number of Internet users in China had reached 705 million by the end of 2015, according to a report by the internetlivestats.com.

In an August 2010 Wall Street Journal article, Baidu played down its benefit from Google's having moved its China search service to Hong Kong, but Baidu's share of revenue in China's search-advertising market grew six percentage points in the second quarter to 70%, according to Beijing-based research firm Analysys International.

It is also evident that Baidu is attempting to enter the Internet social network market. As of 2011, it is discussing the possibility of working with Facebook, which would lead to a Chinese version of the international social network, managed by Baidu. This plan, if executed, would face off Baidu with competition from the three popular Chinese social networks Qzone, Renren and Kaixin001 as well as induce rivalry with instant-messaging giant, Tencent QQ.

On February 22, 2012, Hudong submitted a complaint to the State Administration for Industry and Commerce asking for a review of the behavior of Baidu, accusing it of being monopolistic.

On January 9, 2013, Baidu was still number one in the market, with 64.5% of the users, the closest competitor, Qihoo 360, who launched its own search engine in August, has already taken hold of 10.2% users. Following are Google and Sogou.

By August 2014, Baidu's search market share in China has dropped to 56.3%, where Qihoo 360, its closest competitor who has rebranded its search engine as so.com, has increased its market share to 29.0%, according to report from CNZZ.com.

In February 2015, Baidu was alleged to use anticompetitive tactics in Brazil against the Brazilian online security firm PSafe and Qihoo 360 (the largest investor of PSafe).

Baidu has started to invest in deep learning research and is integrating new deep learning technology into some of its apps and products, including Phoenix Nest. Phoenix Nest is Baidu's ad-bidding platform.

In April 2012 Baidu applied for a patent for its "DNA copyright recognition" technology. This technology automatically scans files that are uploaded by Internet users, and recognizes and filters out content that may violate copyright law. This allows Baidu to offer an infringement-free platform.

Baidu has applied for a utility patent in the UK, for its proprietary site-wise search technology which is currently available in China.

According to the China Digital Times, Baidu has a long history of being the most proactive and restrictive online censor in the search arena. Documents leaked in April 2009 from an employee in Baidu's internal monitoring and censorship department show a long list of blocked websites and censored topics on Baidu search.

In May 2011, activists sued Baidu in the United States for violating the U.S. constitution by the censorship it conducts in accord with the demand of the Chinese government. A U.S. judge has ruled that the Chinese search engine Baidu has the right to block pro-democracy works from its query results, dismissing a lawsuit that sought to punish the company for Internet censorship.

Baidu's reviews are mixed for in many fields and it is controversial. The examples are promoting and commercialization of Baidu Tieba.

In May 2016, Baidu's P4P search results reportedly caused the death of a student who tried an experimental cancer therapy he found online. The 21-year-old college student was named Wèi Zéxī (魏则西), who studied in Xidian University. Wei was diagnosed with synovial sarcoma, a rare form of cancer. He found the Second Hospital of the Beijing Armed Police Corps (武警北京市总队第二医院) through the search engine Baidu, on which the hospital had been promoting itself. The treatment proved to be unsuccessful.

After Wei's family spent around 200,000 yuan (around 31,150 USD) for treatment in the hospital, Wei Zexi died on April 12, 2016. The incident triggered massive online discussions after Wei's death. The fact that Baidu valued money way more than life kindled nationwide rage. On May 2, 2016, Cyberspace Administration of China (CAC), the top watchdog for China's Internet space, dispatched a team of investigators to Baidu. The case is still ongoing. One report claimed medical advertising makes up for 30% of Baidu's ad revenue, much of which comes from for-profit hospitals that belong to the "Putian Network", a collection of hospitals across the country founded by medical entrepreneurs associated with the Putian region of Fujian province. The investigation led Chinese regulators to impose several restrictions on Baidu, including adding disclaimers to promotional content and establishing channels for complaints about Baidu services.

Baidu sold the hemophilia online community, one of the communities of Tieba, to unqualified hospitals. In January 2016, Baidu announced that it will stop selling all of its illness-related Tieba.

Media related to Baidu at Wikimedia Commons