Embedding Dublin Core metadata elements in your web pages provides a standards-based approach to search engine optimization that complements your HTML metadata. The Dublin Core Metadata Initiative is a set of online metadata standards for a broad range of purposes, including semantic tagging to help search engines match requests with relevant results. Because Dublin Core metadata is based on a standard developed by an open organization, embedding Dublin Core metadata in every web page is, in my opinion, a best practice. After briefly discussing the pros and cons of using Dublin Core, this page shows you how to embed DC metadata elements in XML, XHTML, and HTML pages.
Although most major search engines probably do not, at present, assign much weight to Dublin Core metadata, the benefits of using it exceed the cost. The cost is low: taking the time to add it to every web page -- a process that you can easily automate by using your HTML metadata to generate your Dublin Core metadata. Some web developers argue that DC metadata increases code bloat, but this point is tenuous: Most web pages have so much junk code in them that the addition of a small DC block is trivial.
Here's a hypothesis: Given the previous abuse of keywords in HTML metadata, major search engines such as Google give weight to HTML keywords only if they represent and categorize, with exacting relevance, the content of the page. That is, the keywords are parsed as relevant and used only if they also appear in the page's content, title, description, and so forth. Perhaps using Dublin Core metadata keywords that exactly match the HTML keywords and the page's content bolster the weight given to the HTML keywords because the DC metadata keywords lay a foundation of standards-based credibility. Such a hypothesis must, of course, be confirmed by empirical testing, which should be the cornerstone of any approach to search engine optimization.
It's easy to add Dublin Core HTML metadata elements to the HTML header of your page; you simply place the elements within the
<head> element just after your usual HTML metadata. The HTML format of Dublin Core metadata looks like this:
<head> <link rel="schema.DC" href="http://purl.org/dc/elements/1.1/"> <meta name="DC.title" content="SEO with Dublin Core"> <meta name="DC.description" content="How to embed Dublin Core metadata in a web page to provide a standards-based approach to search engine optimization (SEO) that complements HTML metadata."> <meta name="DC.subject" content="seo dublin core, seo dublin core tips, search engine optimization with dublin core"> <meta name="DC.language" scheme="ISO639-1" content="en"> </head>
With XML, you can include Dublin Core metadata in several ways. Here's an example with a DTD -- http://www.criticism.com/xc/xc.dtd -- that I use for some of the pages on Criticism.com. The structure embeds the Dublin Core metadata elements in Resource Description Format (RDF) and extends the
dc:subject element with Prism Controlled Vocabulary (PCV) to encapsulate keywords from a taxonomy:
<rdf:RDF> <rdf:Description> <dc:title>SEO with Dublin Core</dc:title> <dc:description> Embedding Dublin Core metadata elements in your web pages provides a standards-based approach to search engine optimization that complements HTML metadata. This page shows you how to embed DC metadata elements in XML, XHTML, and HTML pages. </dc:description> <dc:subject> <pcv:Descriptor rdf:about="Taxonomy.xml"> <pcv:label>search engine optimization</pcv:label> <pcv:label>Dublin Core metadata</pcv:label> <pcv:synonym>SEO</pcv:synonym> </pcv:Descriptor> </dc:subject> </rdf:Description> </rdf:RDF>
Below is another example in XML, this time using NASA's simple DTD for an RDF-compliant metadata format. "This format is not an offical NASA standard," NASA says. "Instead, it is a recommendation from the NASA Taxonomy Project on what a NASA standard metadata format might look like." For more information or to download the NASA DTD, see http://nasataxonomy.jpl.nasa.gov/fordevelopers/.
<rdf:RDF> <ntmr:Item> <dc:title>Dublin Core SEO</dc:title> <dc:description>How to use Dublin Core metadata to improve search engine rankings. </dc:description> </ntmr:Item> </rdf:RDF>
The format for XHTML is slightly different, as the following example demonstrates. As with HTML, you place the XHTML Dublin Core metadata in the header of your web page just after your usual metadata. This code snippet was automatically generated with the Dublin Core metadata generation engine at http://webposible.com/utilidades/dublincore-metadata-gen/index.php?lang=en:
<link rel="schema.DC" href="http://purl.org/dc/elements/1.1/" /> <meta name="DC.title" content="SEO with Dublin Core" /> <meta name="DC.description" content="How to embed Dublin Core metadata in a web page to provide a standards-based approach to search engine optimization (SEO) that complements HTML metadata." /> <meta name="DC.subject" content="Dublin Core SEO" /> <meta name="DC.language" scheme="ISO639-1" content="en" />
First Published: July 12, 2009. Last Updated: July 12, 2009.