All things being described by RDF expressions are called resources. A resource may be an entire
Web page; such as the HTML document "http://www.w3.org/Overview.html" for example. A
resource may be a part of a Web page; e.g. a specific HTML or XML element within the
document source. A resource may also be a whole collection of pages; e.g. an entire Web site. A resource may also be an object that is not directly accessible via the Web; e.g. a printed book.
Resources are always named by URIs plus optional anchor ids. Anything can have a
URI; the extensibility of URIs allows the introduction of identifiers for any entity imaginable.