Web Design in a Nutshell, 3rd Edition

Link Relationships

The most common use of link relationships in HTML is to link to a style sheet (as explained in Chapter 16). In doing so, the author uses the rel attribute to communicate that the resource “over there” (referenced by the href attribute) is a “style sheet” for the current document. HTML 4 specifically allows for web authors to create and use their own link relationship values, and suggests using a profile to define them. Several popular new link relationship values have emerged to describe, for example, social network relationships between people, licenses for documents, and “tags” for blog posts. Many of these are quickly becoming de facto standards and have been documented as microformats.