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Anchor Text

Anchor text is highlighted words on a page that link to another web page or resource. Clicking on the text, called hypertext, loads the linked resource in the user's browser. Links are created using the Hypertext Mark-up Language's (HTML) anchor element:

    <a href="">This is a hyperlink</a>

The hypertext is the text that occurs between the angle brackets. It would generally appear as: This is a hyperlink in a web browser such as Internet Explorer or Mozilla.

The word hypertext was coined by Ted Nelson who, in the 1960s designed the first ever hypertext system called project Xanadu. Nelson was inspired by a 1945 essay by Vanneva Bush titled: As We May Think. In it Bush envisaged a machine where the user could navigate a non-linear path through a trail of documents linked by concepts represented by words or phrases.

While anchor text tells a search engine nothing directly about the contents of the linked page it is used as a convenient heuristic. A heuristic is a rule of thumb that is normally effective in dealing with a given situation but does not absolutely guarantee the desired results. They are shortcuts where a much more detailed and complicated analysis would otherwise be necessary.

In this case the heuristic is to let humans evaluate the content of the target page. The anchor text should then represent in some way the contents of that page. You can think of it as a vote for your page with those keywords. In an ideal world it should be possible to build quite an effective search engine using anchor text alone. Indeed Oliver McBryan who first proposed the idea at the World Wide Web conference in 1994 used this method on his search engine, the WWW Worm.

There are a couple of pitfalls. Firstly many interesting and useful web pages don't have relevant inbound-links.  Secondly SEO experts can use this knowledge to subvert a search engine to favor their pages by creating inbound links for popular keyword from other sites under their control. This is a form of search engine spam.

Although the concept of hyper-linking seems natural, many site designers still make basic errors with respect to search engine optimization. For example, say you have created a page about problems with four stroke engines. You may have another page with the following text:

Problems with modern four stroke engines are rare but do happen.

You could make a link in a number of places:

  • Problems with modern four stroke engines are rare but do happen.
  • Problems with modern four stroke engines are rare but do happen.
  • Problems with modern four stroke engines are rare but do happen.
  • Problems with modern four stroke engines are rare but do happen.

You could even link the whole sentence. Although the first and last examples may seem logical the anchor text is too vague to be useful. The page is about four stroke engines, so either option 2 or 3 would be better. There are a number of considerations as to which to use. More keywords in the anchor may dilute the importance the search engine gives to each individual keyword, we may want to rank well for four stroke and four stroke engines so adding further anchor text could have a negative impact. We would also have to establish how popular each set of keywords is and how much competition there is for each of them. There is no point going head to head with a popular but generic keyword such as 'engine' (82 million pages returned by Google) if we are unable to put the resources into getting our page into the first twenty or so results returned by the search engines. This is true no matter how popular the search term. If possible avoid stop words such as and, by, from, with as these are not used by search engines when evaluation queries and may dilute the other keywords in the anchor.

Search Engine Optimization Book            

See Also

Inbound-links, Internal-links, Keywords, Keyword Density, Uniform Resource Locators (URLs)

Google Search Operators: Note that allinanchor is no longer mentioned on this page and the equivalent: allinurl doesn't work.

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