Semantic markup can be added to text documents, such as a web page, to explicitly encode the meaning of terms, for example that the words "Alan Dix" refer to a specific perosn, namely the author of this book, as opposed to ther "Alan Dix"s on the web. For web page content there are various lightweight microformats as well as more complex methods to embed RDF, and the schema.org standard encouraged by search engine providers. Semantic markup can allow data from ordinary web pages to be harvested as part of the semnatic web as wella s making web search more precise. Where there is is no explict semantic markup other external semantics technques can be used to look for meaningful units in text.
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