HTML and CSS Reference
In-Depth Information
Listing 7-95. Applying the nofollow Attribute on a Link
<a href="" rel="nofollow">External site</a>
Yahoo! SearchMonkey supports the following metadata [172]:
Microformats, including hCard, hCalendar, hReview, hAtom, hResume, adr, geo, tag, and XFN
eRDF (embedded RDF)
Microformat searches in Yahoo! can be performed easily with queries in the form shown in Listing 7-96.
Listing 7-96. Microformat Search Syntax used by Yahoo! metadata_name
where metadata_name is the name of the metadata in lowercase. RDFa and eRDF searches are similar. The only
difference is that the string uf should be changed to rdf . For example, the hCard microformat can be searched with
the query , RDF in attributes with
rdf.rdfa , and so on.
Metadata annotations such as RDFa can effectively contribute to better search results. The more semantic
content is provided on the Web, the more reasonable and relevant search results can be expected from search
engines. 11 Properly set metadata can help search engines better process and provide personal introductions,
contact data, and full descriptions of persons and human relationships in search results. The indexing of brochure-
style business cards and personal information described in (X)HTML markup, XML, RDF, FOAF, and DOAC is
straightforward. However, semantic contents embedded in conventional markup can be processed only if they
are supported by the mechanisms used by web crawlers. Fortunately, search engines can process more and more
metadata types.
In spite of the huge potential of metadata implementations in search engine optimization, there are several
limitations in real-life applications. For example, image metadata cannot be fully exploited since a large share of social
media and photo-sharing web sites either remove all embedded metadata during upload or apply a new, on-the-fly
generated file without them (even in another file format). Images uploaded to the Internet by anonymous Wikipedia
editors, on the other hand, can be found by their embedded metadata indexed by Google (if available). It is arguable
whether this feature is advantageous.
Similar to any other data, it is important to decide wisely what to publish on the Web. It is no problem at all to
publish the ISBN number of a book or a link to the DBpedia description of a web site item; however, several types
of metadata are risky to publish since they can be abused. Especially e-mail addresses, phone numbers, and instant
messenger screen names should be provided with extreme precaution.
Metadata embedding goes hand in hand with accessibility. Accessibility guidelines can ensure that alternate
content is provided for objects and that the document structure is well organized (Chapter 10).
Some SEO practices do not contribute to user experience (UX) such as frequently repeated keywords that can
decrease human readability [173].
11 Markup is only one thing considered by search engines. For example, well-written, unique, and frequently updated site content is
becoming more and more important for gaining better positions on search results.
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