AOL Instant Messenger was initially integrated into AOL Desktop and later also released as a stand-alone download by America Online (AOL) in May 1997 for Microsoft Windows. AIM was an outgrowth of "online messages" in the original platform (1980's) written in PL/1 on a Stratus computer by Dave Brown. The software, maintained by AOL, Inc., at one time 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 ). This does not include other instant messaging software related to or developed by AOL, such as ICQ and iChat.
Its main competitors during its heyday were ICQ, Yahoo! Messenger and MSN Messenger. AOL particularly had a rivalry or 'chat war' with rival Microsoft starting in 1999. There were several attempts from Microsoft to simultaneously log into their own and AIM's protocol servers. AOL were not happy about this and started blocking MSN Messenger from being able to access AIM.
AIM went officially mobile in early 2008 when the application was released for Windows Mobile devices and allowed for all devices to send IMs via SMS. However AIM could already be used on various devices beforehand with third-party applications, and as early as 2002 on a Sidekick.
After 2012, stand-alone official AIM client software includes advertisements and was available for Microsoft Windows, Windows Mobile, Classic Mac OS, macOS, Android, iOS, BlackBerry OS.
Usage decline and product sunset
Around 2011 AIM started to lose popularity rapidly, partly due to the quick rise of Gmail and its built-in real-name Google Chat instant messenger integration in 2011 and because many people started purely moving onto SMS text messaging and later social networking websites (in particular, Facebook Messenger, which was released as a standalone app the same year) for instant messaging.
As of June 2011 However, this number only reflects installed IM applications, and not active users. The engineers responsible for AIM claimed that they were unable to convince AOL management that free was the future.
, one source reported AOL Instant Messenger market share had collapsed to 0.73%.
On March 3, 2012, AOL ended employment of AIM's development staff while leaving it active and with help support still provided. On October 6, 2017, it was announced that the AIM service would be discontinued on December 15.