What is ICQ?
ICQ is an instant messaging computer program, owned by Time Warner's America Online subsidiary. The first version of the program was released in November 1996. The name ICQ is a play (an oronym) on the phrase "I seek you".
ICQ allows the sending of text messages with offline support, URLs, multi-user character-by-character chats, resumable file transfers, SMSes, greeting cards and more. Other features included a searchable user directory and POP3 email support. Even though such features have been available since around 2000, many of the main competitors such as AOL Instant Messenger, MSN Messenger and Yahoo! Messenger have failed to implement such power-user oriented features even to this day. Instead, they have targeted younger users with an avalanche of colors, avatars, and animations.
ICQ users are identified by numbers called UIN, distributed in sequential order (though it is rumored there are gaps in the sequence). New users are now given a UIN of well over 300,000,000, and low numbers (six or five digits) have been auctioned on eBay by users who signed up in ICQ's early days.
Since 2000, ICQ and AIM users are able to add each other to their contact list without the need of any external clients.
UIN was coined by Mirabilis, to be used as the name of the so called Universal Internet Number that each user of the ICQ instant messaging software is assigned upon registration. Unlike most other instant messaging programs, in ICQ the only information that is permanent to a registered user is the UIN, although users are able to search for users by their e-mail address, much like MSN, or in fact any other detail that the user made public about himself or herself. The screen name may be changed at will, without having to re-register, as can all other kinds of user information, including e-mail.