Gibraltar has always had a special statute in the online gambling world. It is a part of the EU and a UK overseas territory. The United Kingdom Gambling Commission is considered one of the best European gambling regulators, and a Gibraltar license might not have the same value as a UKGC license, but it is the next best thing.
Gibraltar is considered the happy medium between reliability and low taxes but not every casino can get a Gibraltar license. As a matter of fact, new casinos have a slim chance of becoming a Gibraltar licensee as all applicants go through checking procedures and only a handful of them are awarded a license.