Domain Name System, or DNS, is the system on the Internet that resolves names like openvpn.net to an IP address like 220.127.116.11 on the Internet. IP addresses are the unique addresses of computer systems in networks, and the Internet is one big network. These addresses work like phone numbers. They are unique and allow communication between the different computers on the Internet. To expect humans to remember IP addresses for all the various websites they want to visit, is simply not practical. So we create DNS names like openvpn.net, google.com, facebook.com, on the Internet, and let a DNS server take care of translating names to IP addresses. It can also be used for shorter host names in an internal network to resolve a name like pc1 to a private IP address.