It’s the end of an era: Verizon-owned AOL announced on Friday that it will shut down its AOL Instant Messenger (AIM) service, which has been in operation for 20 years,  in December.

“AIM tapped into new digital technologies and ignited a cultural shift, but the way in which we communicate with each other has profoundly changed,” wrote Oath VP of communications product Michael Albers in a Tumblr post. “As a result we’ve made the decision that we will be discontinuing AIM effective December 15, 2017.”

Separately, AOL informed current and past AIM users via email that they will be able to use the service until the shut-down date. After that, all of their data, including their buddy lists, will be deleted. AIM.com email addresses won’t be affected, as they’re effectively just aliases for AOL mail.

AOL had long offered instant messaging within its own online client, but launched a standalone app for AIM in May of 1997. The app competed at the time with various other instant messaging services, including ICQ and Microsoft’s MSN Messenger, but quickly became the most popular messaging app in the U.S.

Some of the features that contributed to its popularity was a buddy list that could be organized to keep track of dozens, if not hundreds of contacts, a profile page and an away status message. In many ways, the latter two preceded many of today’s social networks.

AIM was also popular with users because of the existence of countless of third-party clients, many of which offered some additional functionality, or aimed to merge multiple chat and messaging services in one app. In 2000, a startup even tried to piggyback on AIM to launch a file sharing service dubbed AIMster, which billed itself as a Napster replacement. However, AIMster was quickly sued by the recording industry, and eventually shut down in 2002.

AIM was also one of the first platform for bots, which could be used to access news, play text-based games and more — an idea that was reborn in recent years for messaging on Facebook and elsewhere.

But AIM may be been best known for its iconic running man, which was first introduced as the service’s logo in 1997 and eventually even made it into AOL TV ads. Fittingly, Albers titled the shut-down announcement “Our yellow running man is ready to retire.”