网域名称系统（Domain Name System缩写DNS，Domain Name被译为域名；另外域名服务器Domain Name Server也简称为DNS）是因特网的一项核心服务，它作为可以将域名和IP地址相互映射的一个分布式数据库，能够使人更方便的访问互联网，而不用去记住能够被机器直接读取的IP数串。-The Domain Name System (DNS) is a hierarchical naming system for computers, services, or any resource participating in the Internet. It associates various information with domain names assigned to such participants. Most importantly, it translates domain names meaningful to humans into the numerical (binary) identifiers associated with networking equipment for the purpose of locating and addressing these devices world-wide. An often used analogy to explain the Domain Name System is that it serves as the "phone book" for the Internet by translating human-friendly computer hostnames into IP addresses. For example, www.example.com translates to 208.77.188.166.