The AOL Instant Messenger (AIM) is an ad-supported instant messaging and presence computer program, published by AOL in October of 1997, which uses the OSCAR instant messaging protocol and the TOC protocol.
AIM allows users to communicate instantly through text to their "buddies" (or bots such as SmarterChild or ZolaOnAOL or AOLSafetyBot) around the world, provided they have the AIM software. AIM has 195 million users (January 2003), with a large portion using Internet slang. Advocates claim that it is easy to locate these users by visiting chatrooms that AOL has set up solely for those purposes. Chat topics range from being "alone at home" to "current affairs." AOL also has a member directory where AIM users can locate others online who share their interests. AIM is also noteworthy for its use of buddy icons and buddy profiles, allowing its users to construct a personal avatar and small personal information page.
AIM's setup varies greatly from Windows Live Messenger in that it does not require approval from one buddy to be added to another's buddy list (MSN's default settings notify its users after someone has added them to their list and let them choose whether or not to block that user). As a result, many users keep other unsuspecting users on their buddy list to read their profiles or see if they are online (if the other user had blocked them before), A user can block another user from all communications, but some users keep extra usernames for avoiding these blocks.
Since version 2.0, AIM has included person-to-person text messaging, chatroom messaging, and the ability to share files peer-to-peer with one's buddies. Somewhere in the 4.x series, the AIM client for Microsoft Windows added the ability to play games against one another (This uses the WildTangent engine, which is listed as adware.). Recent (4.3 and later) versions of the client software store one's contact information on AOL's servers, so one can keep track of up to 600 buddies from any computer with Internet access. Stand-alone official AIM client software is available for free for Microsoft Windows, Mac OS, Mac OS X, Linux, Windows CE, and Palm OS. It was believed that versions of AIM including and above 4.0 contained a clause in the software license that disallowed the use of third party clients, so some users still use the 3.0 series of AIM. However, the latest version of AOL Instant Messenger's software license does allow the use of third party clients, subject to the terms and conditions of that third party.
There is also a version of AIM, called AIM Express, that is implemented in DHTML and runs in a web browser. It is intended for use by people who are unable or unwilling to install an executable client on their machines but still want to use instant messaging. AIM Express supports many of the standard features included in the stand-alone client, but does not provide advanced features like file transfer, audio chat, or video conferencing.
The standard protocol that AIM clients use to communicate is called OSCAR. AIM Express uses another protocol called TOC. TOC has also been made available to the public, which some people believe is an attempt to throw a bone to third-party client developers and lure them away from OSCAR. If this is the case, it has not been entirely successful. AOL often changes the details of the OSCAR protocol, which tends to keep third-party clients from working properly. This has resulted in quite a bit of difficulty for programmers of third party clients.
Apple Computer's iChat AV software, released in June 2003 for Mac OS X, was the first AIM-compatible client to allow for audio and video conferencing over the AIM protocol. At that introduction, Apple CEO Steve Jobs announced that iChat was the first AIM client not made by AOL to be officially recognized by AOL. In February, 2004, AIM 5.5 was released, allowing Windows users to video conference with each other and with iChat users. Although AIM is the most feature rich official release of a mainstream instant messenger for the Apple Macintosh, it lacks several features that the latest Microsoft Windows version offers. AOL has announced that they will no longer develop the official AIM client for Macintosh, instead opening the AIM protocol to third parties.
AIM software is the first to use online video streaming advertisements, using ads from EyeWonder.
AOL has recently released its new client software, AIM Triton. Triton is an overhauled version of the AIM client, which has many of the features from the popular third party plug-ins, including tabbed messages and AIM logging. Triton replaces the classic AIM client software. Along with the release of Triton, AOL opened up AIM for developers, allowing anybody to create a plug-in, or AIM custom client. People may also embed AIM online presence on their websites.
AOL has also recently released AIM Mail with the latest version of the AIM client, offering 2GB @aim.com e-mail accounts for all users. Beyond the account size, AIM Mail boasts both webmail and IMAP interfaces, as well as AIM presence and Single Log-on.
AIM is known for security weaknesses that have enabled exploits to be created that use third-party software to perform a myriad of malicious acts on users' computers. Although most are harmless and merely annoying, such as being kicked off the AIM service, others perform potentially dangerous actions such as harvesting IP addresses and sending viruses over a direct connection. Some of these exploits rely on social engineering to spread by automatically sending instant messages that contain a URL accompanied by text suggesting the receiving user click on it, an action which leads to infection. This approach typically makes use of a security hole in Microsoft Internet Explorer as the method of infection.