DNS (Domain Name System) is the technology responsible for resolving a host name to an IP address. It translates domain names, which are easier for humans to remember, into IP addresses that are used by network devices to locate and communicate with each other over the internet. When a user types a domain name into a web browser, the DNS server maps it to the corresponding IP address so the browser can load the desired web page.
Reference: Cisco DevNet Associate documentation on DNS and its functions.