AOL Instant Messenger, released in 1997, was never designed as a consumer hit. It grew out of an internal messaging feature written in the PL/1 language and running on a fault-tolerant Stratus mainframe, built only to move text reliably. Teenagers and college students took it over. By 2006 AIM held 52 percent of the North American instant messaging market, and its away message had turned the family computer into a broadcast tower for song lyrics, inside jokes, and party plans.

This episode covers the rise, the fights, and the fall. Starting around 1999, Microsoft reverse engineered AOL’s closed OSCAR protocol so MSN Messenger users could reach AIM users, and the two companies traded overnight lockouts and patches. AOL then piled on features: chatbots like SmarterChild, AIM Pages, internet phone calls. The software grew bloated, its privacy design let strangers watch users unseen, and text messaging and smartphones finished the job.

• Anyone could add a screen name to a buddy list without approval, then see when that person was online and read their away messages without their knowledge.
• Links beginning with the aim prefix could open a chat window or change an away message straight from a web page, a deep hook that hackers later exploited.
• The Electronic Frontier Foundation’s 2014 secure messaging scorecard gave AIM one point out of seven, for encrypting data in transit.
• By June 2011 AIM’s share of installed apps had fallen to 0.73 percent. AOL laid off most of the development staff in March 2012.
• The servers were shut down on December 15th, 2017. Fans have since revived the service on a nonprofit server called AIM Phoenix.