You may not be aware of it but today there are many different ‘casino networks’ that operate with multiple casinos.
In fact, the majority of online casinos today join a network, like Microgaming, Playtech, 888 Casino Network, TopGame or Cryptologic just to name a few. The key reason that an online casino will join up to a network is that it allows them to offer better and bigger promotions and share games and progressive jackpots … all in the name of attracting more players. As a player, the benefit to you is that there are probably bigger payouts and more lucrative bonuses and prizes (like the progressive jackpot).
However, not all online casinos are a member of network and a handful of the larger, more established ones (usually licensed and regulated by the UK or other European Union countries) can operate independently. But there aren’t many given the high development costs. Two example of independent online casinos are Bodog and Betfair Casino.