How Do the Search Engines Determine Relevance?

How do the search engines determine for any given query which websites to show, and how do they determine which order to show them in?  As we mentioned in our previous tutorial, we are interested in these two questions because the answer will provide us with the knowledge of what it is that we need to do in order to give our site the best chance possible of appearing in the search engines for relevant searches (and not just appearing, but appearing in the top spots).

There are, in general, two factors which the search engines take into consideration when determining their search results.  The first is the content of the actual website itself (in particular, the content of each and every page).  The second is the number and quality of links coming into the site in general, and each page on that site in particular.  These two elements are generally known as on-page factors (i.e., the content of the site) and off-page factors.  Let’s start with the on-page factors.

On-page Factors

It is worth noting that for the most part, your website never competes for a position in the search results.  Only your individual pages compete for those coveted slots.  This doesn’t mean that the overall design and structure of your site doesn’t have a role to play when it comes to optimizing your site.  It has a very important role to play.  Nonetheless, it is individual pages that the search engines results display and as such it is individual pages that compete to show up in those results.  And, for the most part, each and every page on your site gets evaluated in-and-of itself (at least, it is helpful to look at it that way).  As such, the search engines analyze the content on your page to try and determine what it is about.

In particular, it looks at the text on your page and various elements in the code on your page to try and determine what that page is about.  For instance, if a page has a great deal of content about fishing rods, and the phrase fishing rods appears in certain places in your HTML code then the search engine will label that page a fishing rod page.  This doesn’t necessarily mean that that page will rank well for the term fishing rods; after all there may be many other pages which discuss fishing rods and have that term in the relevant places in the HTML code.  What it does mean, though, is that the search engines will not consider this page for unrelated search terms such as balloon rides.  So, in essence, on-page factors tell the search engines what your page is about.  It doesn’t, however, tell the search engines whether your page is the best source for that topic.

What this means is that, ultimately speaking, relevancy is not enough.  There may be thousands, if not millions, of relevant pages for any given search insomuch as they relate in some way or another to the term being searched.  What the search engines really want are the most relevant pages for any given search.  The question is, then, what makes a site more relevant than another.  The answer, for the most part, is links.

Off-page factors

The search engines look at links as a kind of vote.  In theory, people link to sites that they are interested in, and any link that a page receives is an indication that some other site online finds that page worthwhile.  In reality, links are much more complicated than this as we will explain in future blog posts.  For now, though, let it suffice to say that there are quality links, “bad” links and links which are somewhere in-between.  The search engines goal (and they are getting increasingly good at this) is to determine how many quality, relevant links you have coming to your site in general, and each page in particular.  A page which has a large number of high quality links from sites which relate to the topic of that page is considered to be a highly relevant page.

Of course, there are a number of factors that need to be clarified.  For instance, what makes one link a quality link and not another?  How do the search engines determine whether or not two sites are related so that a link from one site to another is considered more valuable?  For now, though, we have enough information to continue with our tutorials.  We know that the search engines determine relevancy based upon the content of our web pages and the number, quality, and relevancy of links coming to those pages.  Our task now is to understand how we use that information to properly optimize our sites for the search engines.  And that is the topic of our next blog post.

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Hi there! Nice stuff, do keep me posted when you post again something like this!

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