PageRank Simplified – What you need to know
January 20, 2005
If you get anywhere near search engine optimization discussions, you’ll hear the term PageRank. There is both a lot of math and a lot of supposition regarding PageRank, but really only a few concepts that you need to know.
When you hear someone talk about what PageRank is, the first thing to remember is that unless the person talking has seen the actual current Google algorithm (a pretty closely guarded secret), what they’re talking about is what we think PageRank is, based on documents published by Google’s staff when they were in college, and based on observations from the outside. The other thing to remember is to insert the word “today” into the discussion, as how PageRank works is something that is constantly changing as the algorithm is adjusted.
Leaving that aside, the basic concept is fairly straightforward, and a general understanding of how it works at Google is probably largely applicable to most of the larger search engines currently, as most of them are using similar techniques.
In a sense, every page that points to your site (your inbound links) is “casting a vote” for your site. From these “votes”, a PageRank of 0 – 10 is calculated for your site.
This PageRank is important, because it is compared, along with your page itself, to other sites to determine which one to list first in search engine results.
In order to calculate your PageRank, the search engine looks at the PageRank of the site that is linking to you. This site’s PageRank is divided by the number of sites it links to, and that “percentage” of PageRank is “how big the vote is”. In other words, if a site that had a PageRank of 10 linked to you — and only to you — you would get a massive amount of PageRank from it. A link however, from a PageRank 2 site that linked to 100 other sites would give you much less by comparison.
From this, we can understand why inbound links to your site are important — without them, your site has no PageRank, and will appear very far down in the search engine results — if it appears at all.
But wait. Search engines don’t link to web sites. They link to pages within web sites. Which brings us to…
Each page of your site is also assigned a PageRank. This PageRank is based on the PageRank of your site, and is “distributed among your pages” by the internal linking structure of your site. The more links between the pages of your site, the better the PageRank is spread out among the pages. Pages that are not pointed to by any other page (yours or someone else’s) will not be included in the search engine, and will not be included in this calculation.
The math involving how PageRank is distributed among the pages of your site is complex (you can learn more here.), so we’ll leave it with the concept that the more your pages link to each other, the more evenly PageRank will be distributed among them, thus improving the chance of each page to be ranked well in the search engines.
From a practical standpoint, this means that on-page navigation, and specialty navigation pages such as topical indexes and sitemaps will improve the disposition of PageRank around your site.
As you may have guessed already, if inbound links bring PageRank, then that must mean that outbound links take it away. This is also true, to an extent, but outbound links are necessary for other reasons involving search engine ranking, as we will see below.
The preceding was PageRank as documented in 1998. PageRank as it is actually used has gone through a number of changes and adjustments that are mostly inferred by results today, along with various information released by Google. The most important of these changes to date has to do with the topicality of links — links from pages that are relevant to your page’s topic are accorded more weight, and (it is widely thought) links that you make to “authority sites” (sites that are seen by the search engine as authorities on the topic) also improve your ranking.
This topic-sensitive PageRank was introduced into Google results in November 2003 as what is called the “Hilltop Algorithm”, and has been under refinement since that point.
It’s also widely thought that sites that have very few outbound links, and sites that link to “less desirable” (in the search engine’s view) pages, such as affiliate links or links to “bad neighborhoods” cause your effective PageRank to be diminished.
From that standpoint, “PageRank leakage” notwithstanding, your site needs to make outbound links, and outbound links to “authority sites” are even better.
How do we know what page the search engine considers an authority on a topic? One good way is by looking at the top search results for that topic.
The PageRank You See
Much like the tao that can be spoken of is not the true tao, the PageRank you can see is not the true PageRank.
How would we see PageRank? If you are still using Internet Explorer (which you shouldn’t be, but that’s another article), you can install the “Google Toolbar”. This will show you a “PageRank” for each page you visit. There is also a plugin for FireFox that will show you the same information.
What you are seeing is “PageRank”, but it is what is considered “Toolbar PageRank” — Google only updates this value occasionally; lately, every few months or so. The “True PageRank” that Google uses (but which we can’t see) is calculated very often.
This means that changes to your site that affect your PageRank will typically affect your search results long before you see a change on your toolbar.
This does not mean that the Toolbar PageRank isn’t useful — it can be very helpful for selecting link partners, but that you need to be aware that it is seldom up-to-date.
What This Means To You
From a practical standpoint, what all this means to a small business web site owner is:
- Links are important. Without inbound and oubound links, your site will not appear in search results.
- The more inbound links you have, particularly relevant ones, the better your search engine results will be.
- Choose outbound links carefully. Links to authority sites can help your ranking, links to “problem” sites can hurt your ranking.
- Your internal site linking structure is important for getting the best possible ranking for your pages.
- Don’t rely on the toolbar PageRank for an up-to-date view of your site’s results.