Patent analysis: how search engines deal with inbound links

This month, Yahoo was granted a patent that describes how link texts may be used to increase the relevancy ranking of a web page. Although the patent was filed in 2002, it provides interesting details about how search engines can use link texts.

Why are link texts important?

All major search engines pay close attention to the text that is used in links pointing to web pages. A web page might be considered more relevant to a search term if the search term not only appears on the web page but is also used in the text of the link that points to the page.

Web pages can even get high rankings for a search term if they don't contain that search term. It's enough that many websites link to the page with the search term in the link text. This has been demonstrated with several Google bombs.

How do search engines treat link texts?

While it is clear that link texts are very important for search engines, it's not clear how much weight search engines assign to a link text when they index a page. Are some link texts more important than others?

The patent indicates that link texts are broken into parts, called tokens:

Once an anchortext phrase is identified, it is converted into a set of tokens. For example, page 306 contains the phrase "best Louis Armstrong site" pointing to page 200. The tokenization produces the following tokens:

* Trumpet"Best Louis Armstrong site"
* "Louis Armstrong"
* "Louis"
* "Armstrong"
* "Best"
* "Best Louis"
* "Best Armstrong"
* "Best site"

The search engine algorithm calculates a weight for each of these tokens. If the weight exceeds a threshold, the linked web page may be indexed under that token.

How do search engines calculate the weight?

Search engines consider how often each word or word sequence can be found in link texts pointing to a particular page and how often the token appears in the index.

Search engines might assign the greatest importance to words that appear the least frequently in the search index. The reason for that is that those words are often more specifically related to the searched topic.

In addition, a token that appears very often in link texts that point to a special web page could be given higher weight. Tokens that appear very frequently in the search index ("site" or "best") might be discounted because they are not relevant to the special topic.

What does this mean to your website?

All major search engines use this method to rank web pages. If you want to get high rankings on search engines, you must make sure that your web site has good inbound links with the right link texts.

Optimized web pages are important to tell search engines that your website is relevant to your keywords. Good inbound links with the right link texts will enforce the relevancy of your pages for your keywords.

What you have to do to get high rankings on Yahoo and Google

1. Optimize your web pages for your keywords. While it is possible to get high rankings for a keyword if you have enough inbound links that contain that keyword, it is much easier to get high rankings for a special keyword if your web page has been optimized for that keyword.

2. Try to get as many inbound links as possible. The links to your website should use your targeted keywords in the link text. Do not use the exactly same text over and over. Vary your link texts and use related but different expressions for the links to your site.


The Yahoo patent confirms the methods that modern search engines use to rank web pages. If you follow the tips and tricks above, your website will get the best possible rankings on Yahoo, Google and other major search engines.

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