The Anatomy of a HyperLink

A standard hyperlink in HTML code looks like this:

<a href="">SEOmoz</a>

In this example, the code simply indicates that the text "SEOmoz" (called the "anchor text" of the link) should be hyperlinked to the page A search engine would interpret this code as a message that the page carrying this code believed the page to be relevant to the text on the page and particularly relevant to the term "SEOmoz".

A more complex piece of HTML code for a link may include additional attributes such as:

<a href="" title="Rand's Site" rel="nofollow">SEOmoz</a>

In this example, new elements such as the link title and rel attribute may influence how a search engine views the link, despite it's appearance on the page remaining unchanged. The title attribute may serve as an additional piece of information, telling the search engine that, in addition to being related to the term "SEOmoz", is also relevant to the phrase "Rand's Site". The rel attribute, originally designed to describe the relationship between the linked-to page and the linking page, has, with the recent emergence of the "nofollow" descriptive, become more complex.

"Nofollow" is a tag designed specifically for search engines. When ascribed to a link in the rel attribute, it tells the engine's ranking system that the link should not be considered an editorially approved "vote" for the linked-to page. Currently, 3 major search engines (Yahoo!, MSN & Google) all support "nofollow". AskJeeves, due to its unique ranking system, does not support nofollow, and ignores its presence in link code. For more information about how this works, visit Danny Sullivan's description of nofollow's inception on the SEW blog.

Some links may be assigned to images, rather than text:

<a href=""><img src="rand.jpg" alt="Rand Fishkin of SEOmoz"></a>

This example shows an image named "rand.jpg" linking to the page - The alt attribute, designed originally to display in place of images that were slow to load or on voice-based browsers for the blind, reads "Rand Fishkin of SEOmoz" (in many browsers, you can see the alt text by hovering the mouse over the images). Search engines can use the information in an image based link, including the name of the image and the alt attribute to interpret what the linked-to page is about.

Other types of links may also be used on the web, many of which pass no ranking or spidering value due to their use of re-direct, Javascript or other technologies. A link that does not have the classic <a href="URL">text</a> format, be it image or text, should be generally considered not to pass link value via the search engines (although in rare instances, engines may attempt to follow these more complex style links).

<a href="redirect/jump.php?url=%2Fgro.zomoes.www%2F%2F%3Aptth" title="" target="_blank" class="postlink">SEOmoz</a>

In this example, the redirect used scrambles the URL by writing it backwards, but unscrambles it later with a script and sends the visitor to the site. It can be assumed that this passes no search engine link value.

<a href="redirectiontarget.htm">SEOmoz</a>

This sample shows the very simple piece of Javascript code that calls a function referenced in the document to pull up a specified page. Creative uses of Javascript like this can also be assumed to pass no link value to a search engine.

It's important to understand that based on a link's anatomy, search engines can (or cannot) interpret and us the data therein. Whereas the right sort of links can provide great value, the wrong sort will be virtually useless (for search ranking purposes). More detailed information on links is available at this resource - anatomy and deployment of links.

Keywords and Queries

Search engines rely on the terms queried by users to determine which results to put through their algorithms, order and return to the user. But, rather than simply recognizing and retrieving exact matches for query terms, search engines use their knowledge of semantics (the science of language) to construct intelligent matching for queries. An example might be a search for loan providers that also returned results that did not contain that specific phrase, but instead had the term lenders.

The engines collect data based on the frequency of use of terms and the co-occurrence of words and phrases throughout the web. If certain terms or phrases are often found together on pages or sites, search engines can construct intelligent theories about their relationships. Mining semantic data through the incredible corpus that is the Internet has given search engines some of the most accurate data about word ontologies and the connections between words ever assembled artificially. This immense knowledge of language and its usage gives them the ability to determine which pages in a site are topically related, what the topic of a page or site is, how the link structure of the web divides into topical communties and much, much more.

Search engines' growing artificial intelligence on the subject of language means that queries will increasingly return more intelligent, evolved results. This heavy investment in the field of natural language processing (NLP) will help to achieve greater understanding of the meaning and intent behind their users' queries. Over the long term, users can expect the results of this work to produce increased relevancy in the SERPs (Search Engine Results Pages) and more accurate guesses from the engines as to the intent of a user's queries.