Domain Name System (DNS) server functions like the internet’s phone book. Whenever you enter a website’s address into your browser’s address bar, your PC forwards that address to the DNS server, and then the DNS server returns an IP address.

Your PC (or phone) uses that IP address to actually send and receive information with whatever website you’re talking to.

DNS servers aren’t strictly necessary for the internet to work, but without them, you’d need to memorize websites’ IP addresses—a daunting task.