[1] Originally developed by the Israeli company Mirabilis in 1996, the client was bought by AOL in 1998, and then by Mail.Ru Group (now VK) in 2010.

[3] ICQ was among the first stand-alone instant messenger (IM) applications—while real-time chat was not in itself new (Internet Relay Chat [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,[4] and its influence is seen in modern social media applications.

In addition the user could change all of his or her personal information, including screen name and e-mail address, without having to re-register.

[9] As such UINs that are stolen could sometimes be reclaimed, if a valid primary email address was entered into the user profile.

[16] In April 2010, AOL sold ICQ to Digital Sky Technologies, headed by Alisher Usmanov, for $187.5 million.

[21] During the second week of January 2021, ICQ saw a renewed increase in popularity in Hong Kong, spurred on by the controversy over WhatsApp's privacy policy update.

According to a Novaya Gazeta article published in May 2018, Russian intelligence agencies had access to online reading of ICQ users' correspondence during crime investigations.

The article examined 34 sentences of Russian courts, during the investigation of which the evidence of the defendants' guilt was obtained by reading correspondence on a PC or mobile devices.

Because the rival service Telegram blocks all access for the agencies, the Advisor of the Russian President, Herman Klimenko, recommended to use ICQ instead.

[27] In 2023, an investigation by Brazilian news outlet Núcleo Jornalismo found that ICQ was used to freely share child pornography due to lax moderation policies.