Semantic HTML: Difference between revisions

Revision as of 20:01, 3 June 2024

Revision as of 20:26, 25 July 2024

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Various versions of the HTML standard have included [[HTML element#Presentation|presentational markup]] such as <code>&lt;font&gt;</code> (added in HTML 3.2; removed in HTML 4.0 Strict), <code>&lt;i&gt;</code> (all versions) and <code>&lt;center&gt;</code> (added in HTML 3.2). There are also the semantically neutral [[span and div]] elements. Since the late 1990s when [[Cascading Style Sheets]] were beginning to work in most browsers, web authors have been encouraged to avoid the use of presentational HTML markup with a view to the [[separation of content and presentation]].<ref>{{cite web|url=http://www.w3.org/MarkUp/Guide/Style.html|title=Adding a touch of style|last=Raggett|first=Dave|date=8 April 2002|publisher=World Wide Web Consortium|access-date=8 December 2010}} This article notes that presentational HTML markup may be useful when targeting browsers "before [[Netscape Communicator|Netscape 4.0]] and [[Internet Explorer 4|Internet Explorer 4.0]]" which were both released in 1997.</ref>

In 2001, [[Tim Berners-Lee]] participated in a discussion of the [[Semantic Web]], where it was presented that intelligent software 'agents' might one day automatically trawlcrawl the Web and find, filter and correlate previously unrelated, published facts for the benefit of end users.<ref>{{cite web | url=http://www.scientificamerican.com/article.cfm?id=the-semantic-web|title=The Semantic Web|first1=Tim|last1=Berners-Lee|first2=James|last2=Hendler|first3=Ora|last3=Lassila|publisher=Scientific American|year=2001|access-date=2009-10-02}}</ref> Such agents are not commonplace even now, but some of the ideas of [[Web 2.0]], [[Mashup (web application hybrid)|mashups]] and [[Price comparison service|price comparison websites]] may be coming close. The main difference between these web application hybrids and Berners-Lee's semantic agents lies in the fact that the current [[news aggregator|aggregation]] and hybridisation of information is usually designed in by web developers, who already know the web locations and the [[Application programming interface|API semantics]] of the specific data they wish to mash, compare and combine.

An important type of web agent that does crawl and read web pages automatically, without prior knowledge of what it might find, is the [[Web crawler]] or search-engine spider. These software agents are dependent on the semantic clarity of web pages they find as they use various techniques and [[algorithm]]s to read and index millions of web pages a day and provide web users with [[Web search engine|search facilities]].