（1）中国互联网络信息中心（CNNIC）对于域名的解释
域名类似于互联网上的门牌号码，是用于识别和定位互联网上计算机的层次结构式字符标识，与该计算机的互联网协议（IP）地址相对应。但相对于IP地址而言，更便于使用者理解和记忆。域名属于互联网上的基础服务，基于域名可以提供WWW、EMAIL、FTP等应用服务。
资料来源：http://www.cnnic.net.cn/html/Dir/2003/11/28/1534.htm
（2）国际互联网名称和地址分配组织（The Internet Corporation for Assigned Names and Numbers，ICANN）对域名的定义
ICANN是域名的管理机构，对于域名的定义应该是最权威的，不过目前从ICANN网站上并没有发现关于“domain name”这一定义，而是关于“Domain Name System”（域名系统）：
What is the Domain Name System?
The Domain Name System (DNS) helps users to find their way around the Internet. Every computer on the Internet has a unique address - just like a telephone number - which is a rather complicated string of numbers. It is called its "IP address" (IP stands for "Internet Protocol"). IP Addresses are hard to remember. The DNS makes using the Internet easier by allowing a familiar string of letters (the "domain name") to be used instead of the arcane IP address. So instead of typing 207.151.159.3, you can type www.internic.net. It is a "mnemonic" device that makes addresses easier to remember.
