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Monday, May 4, 2009

Simple explain of Google PageRank

PageRank is one of the methods Google uses to determine a page’s relevance or importance. "PageRank" or "PR" is a term to indicate the popularity of a page. The popularity of a webpage, according to Google, is determined by the number of links from other pages on the World Wide Web that point to this page.

In this article you can learn :
  • What is PageRank

  • How to check Google PageRank

  • PageRank value

  • How PageRank is calculated (briefly)

  • PageRank facts

  • PageRank algorithm


What is PageRank

PageRank is a “vote”, by all the other pages on the Web, about how important a page is. A link to a page counts as a vote of support. The more votes that are cast for a page, the more important the page must be. PageRank of the page that is casting the vote is very important. Higher PageRank of voter page means better PageRank for voted page.

PageRank does not directly influence a web page's ranking in the search engine results. Google PageRank doesn’t determine which webpages are included in the search results when a search term is entered into Google; that is determined by the relevance of titles, keywords and phrases contained within those pages. But in case two web pages have the same relevance to a search term, Google page rank will determine which page is displayed first in the search results. So Pagerank can be very important for SEO.


How to check Google PageRank

You can check PageRank of web page with Page Rank Checker. In order to check pagerank of web page enter web address and click "Check PR" button.



Another option is to install google toolbar in your web browser. I prefer SearchStatus for Firefox.

PageRank value

PageRank value goes from 0 – 10. Higher pagerank value is better. 0 is bad pagerank value, 10 is best pagerank value.
Page www.google.com is one of most popular pages and has Pagerank 10.
My blog interestigwebs.blogspot.com unfortunately is not so popular and have PageRank (PR) 2.
Each Page Rank level (1 - 10) is progressively harder to reach. PageRank is believed to be calculated on a logarithmic scale.
On the picture you can see approximately number of web sites with different PageRank value (most are in PR 1 and least are in PR 10):

Google PageRank level pyramid

Caution, difference between number of sites for each PageRank value is probably bigger. Picture is only for demonstration purpose.

It is possible to make this classification:
  1. Pagerank 0 - 3 new webpages or those with very few back links

  2. Pagerank 4 - 5 popular pages with a lot of back links from similar sites

  3. Pagerank 6 exceptionally popular sites with hundreds of links from authority sites

  4. Pagerank 7 - 10 usually media brands, big corporations, or government sites



How PageRank is calculated

The PageRank of a particular page is roughly based upon the quantity of backlinks (backlink is a link pointing to a page) as well as the PageRank of the pages providing the links. It is known that other factors, e.g. relevance of search words on the page and actual visits to the page reported by the Google toolbar also influence the PageRank. In order to prevent manipulation, spoofing and Spamdexing, Google provides no specific details about how other factors influence PageRank.


Three most important rules for PageRank:
  • PageRank is based on incoming links, but not just on the number of them - relevance and quality are important

  • Example: for page A is better to have 100 incoming links (backlinks) then 10.

  • PageRank of page on which is incoming link is important

    Example: for page A is better to have incoming link from page B with PageRank 5 then from page C with PageRank 2.

    PageRank of backling page is important


  • PageRank of page on which is incoming link (backlink) is divided by the number of outbound links on that page, more outbound links on page with incoming link means lower PageRank contribution to linked page

    Outbound links - links to other pages
    Example: for page A is better to have incoming link from page B which links only on page A then from same page B which links on multiple pages.

    More outbound links lower PagerRank of linked page



PageRank Facts:

  • Bad incoming links don’t have impact on Page Rank


  • Content is not taken into account when PageRank is calculated


  • PageRank does not rank web sites as a whole, but is determined for each page individually


  • Each Page Rank level (1 - 10) is progressively harder to reach. PageRank is believed to be calculated on a logarithmic scale.


  • Google calculates pages PRs permanently, but we see the update once every few months


  • Links with nofollow-attribute don’t contribute to Google PageRank - if page A have nofollow link to page B, pagerank of page B will not be increased


  • Efficient internal onsite linking has an impact on PageRank


  • Multiple votes to one link from the same page cost as much as a single vote


  • No one knows for sure how PageRank is currently calculated by Google


  • Page Rank can decrease. You can lose some important links that are no longer linking to your site. PR loss can also occur if some of your linking partners also experience a drop in their own PR, possibly setting off a chain reaction of lower PageRank all through the immediate linking network.


  • Site can be banned if it links to banned sites. Don’t link to banned sites, Google will penalize you for bad links so always check the PageRank of the sites you’re linking to from your site.


  • Some people said that bounce rate influence on PageRank in new Google PageRank algorithm, author of this article is doubtful for this



PageRank Algorithm

The formula is:

PR(A) = (1-d) + d (PR(T1)/C(T1) + ... + PR(Tn)/C(Tn))

  • PR(A) is the PageRank of page A

  • PR(Ti) is the PageRank of pages Ti which link to page A

  • C(Ti) is the number of outbound links on page Ti

  • d is a damping factor which can be set between 0 and 1


PageRank of page A is defined by the PageRanks of those pages which link to page A.
PageRank contribution of page T to page A is always weighted by the number of outbound links C(T) on page T. This means that the more outbound links a page T has, the less will page A benefit from a link to it on page T.
Finally, the sum of the weighted PageRanks of all pages Ti is multiplied with a damping factor d which can be set between 0 and 1.

For more details about PageRank algorithm check:


Impact of transition from PR 1 to PR 2 on my blog

PageRank of my blog increased to PageRank 2 from PageRank 1 in beginning of April. It has impact on visits. In March there was 1010 unique visitors while in April there was 1889 unique visitors.

Visitors impact of growth PR 1 to PR 2 on my blog


Terms:

Backlinks - are incoming links to a web page. Backlinks are also known as incoming links, inbound links, inlinks, and inward links.

Hyperlinks - clickable link in text or an image on a web page that takes you to another location within the same document, web page, web site or to a completely different location.

Link Popularity - refers to the total number of inbound links to a particular web site by different search engines such as Google, MSN, Yahoo etc.

Nofollow - is an HTML attribute value used to instruct some search engines that a hyperlink should not influence the link target's ranking in the search engine's index. It is intended to reduce the effectiveness of certain types of search engine spam, thereby improving the quality of search engine results and preventing spamdexing from occurring.

Outbound links - these are links that direct the Internet user to another websitelinks, to another pages

PR - PageRank, a Google patented method for measuring page importance or relevance; ranges from 0 to 10, 10 being the best.

Spamdexing - (also known as search spam or search engine spam) involves a number of methods, such as repeating unrelated phrases, to manipulate the relevancy or prominence of resources indexed by a search engine, in a manner inconsistent with the purpose of the indexing system

Spoofing - impersonating another person or computer, usually by providing a false email name, URL or IP address.



Further information and resources:

The Google Pagerank Algorithm and How It Works
PageRank Wikipedia
Pagerank-building


Related articles:


Bguide: Alexa traffic rank

10 comments:

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Web Development said...

Very interesnting and useful information.

SEO Secrets said...

Your post is a good resource on PageRank.

Anonymous said...

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nida said...

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Nitin said...

ultimate knowledge for SEO beginners.

Arnel Colar said...

Can blogger sites like yours (domain.blogspot.com) go up to more than PR3?

Most suggests that I should have to host my own site to help increase PR faster.

Mark said...

To Arnel Conral:
In my opinion PR is not connected with blogspot domain.
You just must have enough backlinks from other high PR sites.
After I read your question I tried to find high PR blogspot blog.

For example:
http://scribbit.blogspot.com/ PR5
or
http://cooladzine.blogspot.com/ PR4

One of the ways to improve PageRank is to write guest posts on blog with a high PR.
If you interested you could try to write one guest post for me. If I published it I will put a link to your page on my main page (PR 2) for three months.

Computer Tips and Tricks said...

this one is something. i think any think can get page rank