DNS is the Internet's phonebook. Whenever you type in or click a human-readable web link (such as hpe.com), your web browser calls on a domain name system (DNS) resolver to resolve its corresponding Internet Protocol (IP) address.
DNS is essential. Without it, there is no Internet. Period. End of statement.
DNS is not just for browsers, though. If it runs on the Internet—Slack, email, you name it—DNS works behind the scenes to make sure all the application requests hook up with the appropriate Internet resources.