VPN jurisdiction is, in a nutshell, where a VPN's headquarters is based – and it's an important factor to consider when hunting for a new service. Why does it matter, you ask? Well, different countries have different attitudes toward data retention, and some even have mandatory data sharing and surveillance laws that a VPN, if based in such a country, has to abide by.
The best VPN services are those that are based outside the clutches (jurisdictions) of multi-nation alliances, such as the Five Eyes, Nine Eyes, and Fourteen Eyes. This means they cannot be compelled to spy on their users, log their activity, or hand it over to the authorities.
