DNS stands for Domain Name System. It converts a domain name (e.g. www.mustermann.de) into an IP address. This is comparable to a telephone book in which each subscriber is resolved into a telephone number.
It thus offers a simplification because people can remember names much better than columns of numbers. To the example you can remember the domain name www.checkdomain.de better than the corresponding IP address 220.127.116.11.
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