Regulated online poker sites are generally publicly traded companies that work in conjunction with governments around the world to offer online poker.
It’s not all positive for regulated online poker sites, however, as they operate in fewer countries and tend to offer less financial incentives for players because they are beholden to shareholders.
Meanwhile, unregulated online poker sites are generally available in more jurisdictions but are not officially permitted. That means that you never know how long these sites will operate. Most unregulated online poker sites have paid back players if they are forced to leave a market but you are exposing yourself to some amount of risk by playing on those sites.
Your best practice will probably be to avoid holding a large amount of funds on unregulated online poker sites.