>>15032024pokerroom.com was one of the first commercial online real-money poker sites. they were legal in the US until 2006 when it was uncovered that the major sites were using insiders to cheat. I was on pr from 2000-2002 and it was easy pickings.
One result of the banning of these sites in the US was that every hand history had to be saved and made available to all players. This initiated the programs that real players use to track the betting tendencies, wins, and losses of other players. Using these programs is literally the only way to make money online now. But in the early days, it was straightforward tight/aggressive poker that won the pots.