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ICQ

IQ LLC
Icq new 1024.png
Initial release November 15, 1996; 20 years ago (1996-11-15)
Stable release
10.0 Build 12094 / June 27, 2016; 8 months ago (2016-06-27)
Operating system Microsoft Windows, macOS, Android, iOS, Windows Phone, Symbian, Linux
Type client
License Proprietary (Adware), Linux version under Apache license 2.0
Website Official website

ICQ is an open source instant messaging computer program that was first developed and popularized by the Israeli company Mirabilis in 1996. The name ICQ derives from the English phrase "I Seek You". Ownership of ICQ passed from Mirabilis to AOL in 1998, and from AOL to Mail.Ru Group in 2010.

The ICQ client application and service were initially released in November 1996 and the client was freely available to download. Users could register an account and would be assigned a number, like a phone number, for others to be able to contact them (users could also provide handles). ICQ was the first stand-alone instant messenger and the first online instant messenger service as such — while real-time chat was not in itself new to the internet (IRC being the most common platform at the time), the concept of a fully centralized service with individual user accounts focused on one-on-one conversations set the blueprint for later instant messaging services like AIM, and its influence is seen in modern social media applications.

At its peak around 2001, ICQ had more than 100 million accounts registered. At the time of the Mail.Ru acquisition in 2010, there were around 42 million daily users. Since 2013 ICQ has 11 million monthly users.

ICQ provides all users additional services and content products:

Also, users can choose and select their own avatar for their profile page. In this way, they can protect their privacy.

ICQ users are identified and distinguished from one another by UIN, or User Identification Numbers, distributed in sequential order. The UIN was invented by Mirabilis, as the user name assigned to each user upon registration. Issued UINs started at '10,000' (5 digits) and every user receives a UIN when first registering with ICQ. As of ICQ6 users are also able to log in using the specific e-mail address they associated with their UIN during the initial registration process. Unlike other instant messaging software or web applications, on ICQ the only permanent user info is the UIN, although it is possible to search for other users using their associated e-mail address or any other detail they have made public by updating it in their account's public profile. In addition the user can change all of his or her personal information, including screen name and e-mail address, without having to re-register. Since 2000 ICQ and AIM users are able to add each other to their contact list without the need for any external clients. As a response to UIN theft or sale of attractive UINs, ICQ started to store email addresses previously associated with a UIN. As such UINs that are stolen can sometimes be reclaimed. This applies only if (since 1999 onwards) a valid primary email address was entered into the user profile.


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