Domain Name Server – computer that translates human-friendly URLs (words) into computer-friendly IP addresses. This process occurs every time a user requests a page from a website. The main function of the nameserver is to store a “zone file” of a domain, where all domain information is kept (registration data, host records, etc.)
Nameserver is a server on the Internet specialized on handling queries about location of domain name’s various services.
Nameservers are a fundamental part of Domain Name System. They allow to use domains instead of IP addresses. It is like contacting your friend by phone: before calling, you look up his telephone number or write it down not to enter the numbers each time.
In easy words, nameservers define your domain’s current DNS provider.