AOL was a big early Internet service provider, and of course by the late nineties, the most popular Internet protocol was the web; most users spent most of their Internet time in a web browser.
But if you go back a few years before that, say before 1993, before the web existed, that was still the era of Windows, when people expected a graphic user interface.
What client program, what user interface, did AOL provide for its subscribers at that time?