Backlinks and PageRank (PR)
The SEO value of a page may change significantly and be unexpectedly high or unexpectedly low. We discussed this topic in the article How PageRank Works.
The article explains the PR algorithm, with an example of the original mathematical calculation that Google used many years ago to evaluate web pages. Things have changed a lot since then. However, Google still score every web page on the Internet.
The score is a value between one and ten—this score is for internal use only. PageRank values were once public: in March 2016, Google confirmed the removal of the PR Toolbar. Already at that time, Google had stripped away PageRank values from Toolbars and browsers, which they hadn't updated in years.
The web crawlers "look" at all the web pages on the Internet. Crawlers index the links and retrieve web page data to calculate the value of every web page.
In the article we previously mentioned on how PageRank works, we illustrated how to calculate PR for a five-page internet.
Let's consider five pages A, B, C, D and E of a simplified website. These pages are all linked as we typically do to guide the user to search for products, services and information. The following image shows the distribution of PR with several links between pages. The actual PR distribution amongst pages may come as a surprise.
A similar yet more complex situation occurs if we consider websites in place of pages.
Managing the interlinking between pages can represent a bit of a challenge for most of us. When we move to a small internet of five websites with a few pages each, things are even more complicated to work out and ultimately to understand. Now we are dealing with links coming from different pages within those sites. Let's go back to the BBC example we mentioned earlier: keep in mind the Internet's pyramid structure. Many websites have a similar structure. It's easy to understand the difference between a backlink from the BBC's Home Page and one coming from a news article nearly 20 years old.
Let's consider our tiny Internet web of ten pages - the challenge is to identify the best page for a backlink. It's not easy to see because the PR scores vary significantly.