DNS, which stands for "Domain Name System," works like a phone book that converts a domain name or website name into an Internet protocol (IP) address, a unique number that identifies every device on a network. DNS enables users to look up a website or send an email through a memorable name, instead of having to remember and type in its IP address.
For example, anyone with a working Internet connection can simply type in "facebook.com" into a Web browser to get to Facebook's website. The computer first connects to a DNS server to look up Facebook's IP addresses, one of which is 184.108.40.206. This process is called DNS name resolution. The computer then communicates with the server corresponding to the IP address, enabling the user to see the Facebook site. An Internet browser can still look up a site using IP addresses, but domain names such as Facebook.com or Google.com are far easier to remember than a string of numbers.
The origins of DNS date back to the ARPANET era, when the Stanford Research Institute maintained a database of server names and their corresponding numerical addresses in a hosts.txt file. As the network grew rapidly, the process had to be automated. This paved the way for the development of the first DNS servers.