Search engines work on the assumption that the most important parts of a website are those that are the most visible to users.
For instance, if most links and users land of the homepage, and the homepage links to three subpages, search engines assume that after the homepage these three subpages are the most important (and the pages linked to by those are the third most important pages). It does this through the flow of link equity.
Link equity is calculated by creating a graph of every link on Internet and letting each page inherit equity from the pages linking to it (for simplicity, we will assume that certain ‘seed pages’ are given equity at the beginning of the process and this flows through the entire Internet). To avoid link equity flowing infinitely, with every link the equity degrades by a certain percentage (in our theoretical model, this will be 10%).
In this system we have five websites, only two have links in from outside the system (the red and green websites have a link equity score of 100). Each arrow is a standard hyperlink through which an equal amount of link equity flows.
The interesting features to note are the degradation of link equity through each link – if you had a massive website and your most valuable pages were 5 or so clicks from the pages with the most link equity, much of this will have eroded by the time it reaches the valuable pages. This also shows the importance of getting other websites to link to your most valuable pages or pages within one click of them (i.e. a popular guide on how to install a bath is a very ‘linkable’ asset that can link directly to your bath product page).
It is important to note that subpages can be more valuable than your homepage. This is uncommon on the Internet in general, as homepages tend to be linked to most often, but it can happen when you have one very popular section of a website (such as the video streaming section of a TV network’s corporate website).
The third thing to learn from this system is the fact that the more links you have on one page, the less link equity flows to each. Obviously not every page on your site has the same value – certainly your terms and conditions or contact page is probably not as important for users as your main product page. For this reason, it is generally best practice to structure your website in a pyramid hierarchy – with only the most useful/valuable pages linked to from the homepage and main navigation, and less important pages linked to from subpages.Next: Links, Co-citations, and Unlinked citations >