Tencent QQ, generally referred to as QQ, is the most popular free instant messaging computer program in Mainland China, and the world’s third most popular IM service . The program is maintained by Tencent Holdings Limited (HKEX: 0700), owned in part by Naspers. Since its entrance into Chinese households QQ quickly emerged as a modern cultural phenomenon, now being portrayed in popular culture. Aside from the chat program, QQ has also developed many subfeatures including games, pets, ringtone downloads, etc.
The original name of QQ was OICQ. The name was based on an already existing IMS (Internet Message Service), "ICQ".
ICQ was one of the first IMS programs. The acronym "ICQ" came from the fact that the letters sound like "I seek you".
"OICQ" stood for "Oriental ICQ" but because of possible trademark infringement was changed to "QQ"
There were 341 million active QQ accounts as of September 3, 2008, and it is estimated that there are over 160 million QQ users in China. But because some users own two or more IDs it is hard to know the exact user amount. As of 14 May 2008, there are an average of 30~40 million accounts online at day time on the Mainland China server.
Outside of China, QQ usage is extremely limited, except in South Africa, where it has been used for at least two or three years and has inspired a song by local band The Finkelsteins called "QQ Me". QQ is used by people who want to communicate with people inside those countries. Examples include expatriates, international students and people studying Chinese.
Tencent was founded in Shenzhen, China in November, 1998. Tencent’s instant messaging service platform, "QQ," was formally launched in February 1999. After years of strong business growth, on July 16, 2004, Tencent Holdings Limited (SEHK 700) went public
QQ was initially developed by Tencent Inc. in February 1999. It was first released as a "Network Paging" real time communications service. Then other features were successively added such as chatrooms, games, personal avatars (similar to "Meebo" in MSN), internet storage, and internet dating services. Most of these features were free. Its variety of features and easy-to-use interface made it very popular, especially among teenage users. In a few short years it was the most popular real time communications service in China.
The current version of QQ is QQ2008II Beta 1. Tencent periodically releases special versions of QQ to coincide with events such as the Olympics or Chinese New Year.
The official client runs on Microsoft Windows and a beta public version were launched for Mac. The web version, which makes use of Ajax, is currently in Beta. On July 31th, 2008 Tencent released an official client for Linux. 
In response to competition with Windows Live Messenger, Tencent released Tencent Messenger, which is targeted to business people. It also provides, in limited form, features that are only available to premium members in normal QQ.
QQ currently allows free registration for membership. In 2002, Tencent had stopped its free membership registration, requiring all new members to pay a fee. However, free registration was reopened in 2003 due to pressure from other instant messaging services such as Windows Live Messenger and Sina UC. Tencent currently offers a premium membership scheme, which offers features such as mobile QQ, ringtone downloads and SMS sending/receiving. In addition, Tencent offers Diamond noble memberships. Currently, there are seven diamond services available:
- Red, for the QQ show service.
- Yellow, for the Qzone service which is similar to a blog.
- Blue, which is for QQ games.
- Purple, which is shared between three Tencent games, QQNana, a Korean dancing game, QQTang, an action game, extremely similar to crazy arcade, and QQSpeed, a race game.
- Pink, for QQ pet, a small desktop game about raising a pet. So far there are 3 generations of pets. Penguin, Pig, and Bear (Beta testing).
- Green, for QQ music, which is a software for listening to music directly from the Tencent server. Requiring no pre-download and sometimes consuming a lot of disk space due to caching.
- VIP, for chat, beta test things, no advertising and some more
- Black (introduced more recently) DNF which is 地下城与勇士 in Chinese is a Tencent game which contain PVP
Tencent taken advantage of the popularity of the QQ brand, and have set up many Q-Gen stores selling QQ branded merchandise such as bags, watches, clothing as well as toy penguins.
 Controversies and criticisms
QQ has faced many criticisms and controversies. Many users complain QQ provides fewer and fewer free services and an annoying number of ads.
 Adware classification
 Keyword filtering
On August 2004, QQ Games began filtering keywords such as "钓鱼岛" (Diaoyu Islands) and "保钓" (Movement to protect the Diaoyu Islands). This act caused much controversy and Tencent has since lifted the filter.
 QQ real group name scheme
On July 21, 2005, Tencent announced its intention to follow orders set by Shenzhen Police and enforce the requirement of real names for all the administrators and founders of QQ Groups. This caused much controversy on whether it can prevent the spread of pornographic and other indecent messages, or whether it intrudes on one’s privacy. However, the difficulty of enforcement made the real name registration optional. 
Tencent QQ has been known to copy its competitors’ features. The interface of early version of Tencent messenger was almost identical to ICQ, but as it developed, it started to look more like Windows Live Messenger. The interface of QQ is Luna themed. In addition to interfaces, QQ has also been known to copy code and text from its competitors. For example, one release contained Skype‘s EULA, allegedly as an April Fools’ Day joke.
 Resource usage
The resources required to run QQ have increased substantially since it was first released, which has caused some people to turn to third party "lite" versions. Pidgin, a free alternative to proprietary instant messaging clients, supports the QQ protocol.
 QQ Coin
The QQ coin is a virtual currency used by QQ users to "purchase" QQ related items for their avatar and blog. QQ Coins are obtained either by purchase, one coin for one RMB, or for using the mobile phone service. Due to the popularity of QQ in Chinese young population, QQ coins are now accepted by gradually more and more online stores and gaming sites in exchange for "real" merchandise such as small gifts, and raised the concern of replacing (and thus "inflating") real currency in these transactions. The People’s Bank of China, China’s central bank, says it is investigating the possibility of cracking down on QQ coin, due to people using QQ Coins in exchange for real world goods. Tencent claims the QQ coin was merely a regular commodity, and thus not a currency. 
Coral QQ, a modification of Tencent QQ, is a popular add on. While Tencent charges for some services and displays advertisement, Coral QQ, provides free access to some of the services and blocks Tencent’s advertisements. In 2006, Tencent filed a copyright lawsuit against Chen Shoufu (aka Soff), the author of Coral QQ, whose redistributing modified Tencent QQ was ruled illegal. Chen then published his modification as a separate add on. On August 16, 2007, Chen was detained again for allegedly making profits off his ad-blocking add on. His case is pending at Shenzhen Nanshan district court.
 Open source and cross-platform clients
Using reverse engineering, open source communities have come to understand the QQ protocol better and have implemented client core libraries and user-friendly clients. Most of these clients are cross-platform, so they are usable on operating systems which the official client does not support. However, these implementations have only a subset of the functions of the official client and therefore are more limited in features.
- Adium, an open source multiprotocol client for Mac OS X
- Pidgin, an open source cross-platform multiprotocol client
- Carrier, an open source cross-platform multiprotocol client based on Pidgin.
- Miranda IM, an open source multiprotocol client, designed for Microsoft Windows
- Instantbird an open source multiprotocol client that uses software from Pidgin and Mozilla
- Eva IM client is a client for the K Desktop Environment (KDE) that can be used to access the QQ network.
- LumaQQ Is an open source QQ client using the Java SWT implementation.
- TextQQ Is an open source command line QQ client that uses the LumaQQ core library.