What is DNS?
DNS stands for Domain Name System. It syncs up web domain names (e.g. www.expressvpn.com) with IP addresses (e.g. 172.16.254.1), enabling users to use domain names to access IP addresses without needing to remember the IP addresses.
How does DNS work?
Think of DNS as a phone book for the internet associating phone numbers (IP addresses) with people (website URLs). DNS servers are maintained by a number of different entities, though most users default to the ones maintained by their internet service providers.
VPNs like ExpressVPN use their own DNS servers, which helps to hide user activity from the ISP and prevents websites from geographically restricting content.