rel is short for "relationship" and an HTML 4.01 attribute on the
link elements. The 'rel' attribute is used for several popular elemental microformats such as rel-nofollow, rel-license, rel-tag, and XFN. Popularity is noted as of 2005-12 per the Google study on markup use, in particular the use of link relationships, the <a> tag, and related page headers (which noted that "XFN [is] the most popular HTML metadata profile").
For more on the
rel attribute and its use in microformats, see:
Specifications and drafts:
- XFN: rel-acquaintance, rel-contact, rel-friend, rel-me and other xfn values.
See existing-rel-values for a more comprehensive list of rel values from HTML4, microformats, and other sources.
Articles and other tutorials written about the "rel" attribute and microformats use of. Most recent first.
See articles for more articles on microformats in general.
RDFa defines a processing model for rel values that is incompatible with both previous HTML usage of rel (e.g. HTML4), and modern microformats and HTML5 definitions and usage (document scoped).
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