Regulated brokers are registered with their country’s financial regulatory body (for example, the FCA in the UK) and who must comply with the rules set down by that body. When a broker is unregulated, there is no regulatory organization or group of persons monitoring them. Still, unlicensed brokers, or unregulated, are very common and they are not illegal. The main thing you stand to lose if you deal with them is your access to recourse. Regulated brokers are not guaranteed to treat you well, but they are guaranteed legal scrutiny if they break the rules.