Domain Name System (DNS)
Domain Name System, or DNS is a system that resolves and matches domain names and IP addresses of servers and devices on the Internet. All devices and/or services connected to the Internet, including servers are identified by two IP addresses, IPv4 and IPv6. In order to access information contained in these servers, a device needs to request it with the IP address. However, IP addresses are long strings of number which are difficult to remember for humans (e. g. 220.127.116.11 for Google.com).
DNS provides a way to match these IP numbers to a domain name that uses words and letters, making it easier for humans to remember and recognize. The first version was invented by Paul Mockapetris in 1983. Although the name to number system was used since the days of ARAPNET, DNS provided hierarchical, automatic, distributive method of doing so that was less vulnerable to crisis.