The Domain Name System (DNS) is a crucial component of the Internet. Whenever you visit a website, send an e-mail, or do anything on the Internet, DNS helps you get to the right place.
Think of the DNS as the Internet's phone book. In the same way that a phone book keeps an index of phone numbers, DNS keeps an index of IP addresses for different websites. IP addresses are computer-readable combinations of numbers that act as the authoritative address of websites. Everything on the Internet has an IP address, but we do not expect humans to remember that 22.214.171.124 is computer-speak for www.opendns.com. Therefore, we employ the DNS in order to help us connect to computer systems all over the world without having to remember and recall all of these IP addresses.