1. (尤指某人有控制力、影响力或权利的)领域，范围，范畴
    A domain is a particular field of thought, activity, or interest, especially one over which someone has control, influence, or rights.

    e.g. ...the great experimenters in the domain of art...
           艺术领域伟大的实验者们
    e.g. This information should be in the public domain.
           这一消息应该为公众所知。

2. 领土;势力范围
    Someone's domain is the area they own or have control over.

    e.g. ...the mighty king's domain.
           势力强大的国王的领土

3. (因特网上的)域
    On the Internet, a domain is a set of addresses that shows, for example, the category or geographical area that an Internet address belongs to.