From Tim Wu’s Attention Merchants pg 202:
Among the sources of such comfort would be AOL’s infamous chat rooms. Chat rooms had actually been invented by CompuServe in the 1980s (under that ’70s handle “CB simulator”), but AOL allowed the creation of “private rooms,” which anyone could open, hosting up to twenty-three total strangers. By 1997, they would claim to have nineteen thousand different rooms. One key to this success: AOL had female users—not many, but enough to create a completely different atmosphere than the average CompuServe chat room, which might be, for example, a group of dudes conversing in medieval English. CompuServe may have had much the same setup, but being distinctly and persistently inhabited by hard-core computer users and other breeds of geek and nerd, they just didn’t know how to get the party going, not one the general public would care to join anyway. (A note to puzzled younger readers: in the 1990s, nerd-cool had not yet been invented.)
They also began to exploit ‘big data’ long before the modern giants, as was true of Yahoo as well. From pg 211:
Years before Facebook or Google undertook a similar mission, AOL’s business team also began coming up with ways to cash in on the “big data” they had collected: that is, the addresses, phone numbers, and credit card numbers of millions of users. The walled garden, by its nature, was already giving companies direct access to users and some of their information; now AOL also began allowing them, for instance, to insert ads into emails (making the service, in effect, a spammer of its own users). But there were more audacious plans still. AOL sold its users’ mailing addresses to direct mail companies. It was going to sell the phone numbers to telemarketers as well, shamelessly describing these maneuvers in its terms of service as a membership benefit. Alas, an inadvertent leak of the plan prompted a user revolt and the telemarketing part was abandoned.