[2] AIM was an outgrowth of "online messages" in the original platform written in PL/1 on a Stratus computer by Dave Brown.

At one time, the software had the largest share of the instant messaging market in North America, especially in the United States (with 52% of the total reported as of 2006[update]).

[8][9] This led to efforts by many companies to challenge the AOL and Time Warner merger on the grounds of antitrust behaviour, leading to the formation of the OpenNet Coalition.

[10] Official mobile versions of AIM appeared as early as 2001 on Palm OS through the AOL application.

[16] Around 2011, AIM started to lose popularity rapidly, partly due to the quick rise of Gmail and its built-in real-time Google Chat instant messenger integration in 2011 and because many people migrated to SMS or iMessages text messaging and later, social networking websites and apps for instant messaging, in particular, Facebook Messenger, which was released as a standalone application the same year.

The engineers responsible for AIM claimed that they were unable to convince AOL management that free was the future.

[2] On March 3, 2012, AOL ended employment of AIM's development staff while leaving it active and with help support still provided.

[24] In April 2015, the Running Man was officially featured in the Virgin London Marathon, dressed by a person for the AOL-partnered Free The Children charity.

However, AOL also created a simpler protocol called TOC that lacks many of OSCAR's features, but was sometimes used for clients that only require basic chat functionality.

[30] Under the AIM Privacy Policy, AOL had no rights to read or monitor any private communications between users.

This was outlined in the policy and terms of service: "... you grant AOL, its parent, affiliates, subsidiaries, assigns, agents and licensees the irrevocable, perpetual, worldwide right to reproduce, display, perform, distribute, adapt and promote this Content in any medium".

AOL stated that it had taken great pains to ensure that personal information will not be accessed by unauthorized members, but that it cannot guarantee that it will not happen.

The more useful chat bots had features like the ability to play games, get sport scores, weather forecasts or financial stock information.

This was similar in function to the mailto: URI scheme, which created a new e-mail message using the system's default mail program.

AIM had security weaknesses that have enabled exploits to be created that used third-party software to perform malicious acts on users' computers.

[34] Although most were relatively harmless, such as being kicked off the AIM service, others performed potentially dangerous actions, such as sending viruses.

Some of these exploits relied on social engineering to spread by automatically sending instant messages that contained a Uniform Resource Locator (URL) accompanied by text suggesting the receiving user click on it, an action which leads to infection, i.e., a trojan horse.

These messages could easily be mistaken as coming from a friend and contain a link to a Web address that installed software on the user's computer to restart the cycle.

Included in the update was a brand new iOS application for iPhone and iPod Touch that incorporated all the latest features.

The user-interface was entirely redone for the features including: a new buddy list, group messaging, in-line photos and videos, as well as improved file-sharing.

[36] Version 5.0.5, updated in March 2012, it supported more social stream features, much like Facebook and Twitter, as well as the ability to send voice messages up to 60 seconds long.

It supported geolocation, Facebook status updates and chat, Myspace, Twitter, YouTube, Foursquare, and many other social networking platforms.

[39] It was an upgrade to the prior AOL Quick Buddy, which was later available for older systems that cannot handle Express before being discontinued.

The main focus of AIM Pages was the integration of external modules, like those listed above, into the AOL Instant Messenger experience.

The application provides visually impaired users the ability to convert messages from text (words) to speech.

The service, however, was only free for receiving and AOL charged users $14.95 a month for an unlimited calling plan.

[55] On November 4, 2014, AIM scored one out of seven points on the Electronic Frontier Foundation's secure messaging scorecard.