วันจันทร์ที่ 12 มกราคม พ.ศ. 2552

Google PageRank Explained

1. What is PageRank?
Here is what Google says:

" PageRank relies on the uniquely democratic nature of the web by using its vast link structure as an indicator of an individual page's value. In essence, Google interprets a link from page A to page B as a vote, by page A, for page B. But, Google looks at more than the sheer volume of votes, or links a page receives; it also analyzes the page that casts the vote. Votes cast by pages that are themselves "important" weigh more heavily and help to make other pages "important."

<a target="_new" href="http://www.google.com/technology/">Click here for more... </a>

In other words, PageRank is simply a mechanical algorithm by Google that attempts to evaluate the importance of your website larged based on the amount and quality of backlinks your website have. For the more intellectual crowds out there, check out <a target="_new" href="http://dbpubs.stanford.edu/pub/showDoc.Fulltext?lang=en&doc=1999-66&format=pdf&compression=&name=1999-66.pdf">The PageRank Citation Ranking: Bringing Order to the Web</a>.

2. How do I check the PR of a webpage?
If you use Internet Explorer, download and install the <a target="_new" href="http://www.google.com/toolbar.html">Google Toolbar</a>. There will be a green ind icator on the toolbar that tells the PR of a particular page. Hovering your mouse over the ind icator will give you a numeric value of the PR. In addition, there are numerous tools out there that will check the PR of a page without the toolbar (do a search on Google). If you use Mozilla Firefox, you can install the <a target="_new" href="http://pagerankstatus.mozdev.org/">PageRank Checker</a> extention.

3. Why do I want a higher PR?
It used to be believed that a higher PR value will give you a higher position in SERPs (Search Engine Results Pages). However, this is no longer the case. As any experienced webmaster, and even <a target="_new" href="http://www.google.com/webmasters/4.html">Google themselves</a>, would tell you, there are hundreds of factors that determine where your page is displayed in the results.

Google states that they do not recommend webmasters exchange links to increase their PR. They see it as trying to "game" their search engine. Lastly, many people believe that a higher PR causes Googlebot to crawl through a page more often.

4. Is it a good idea to buy links for a higher PR?
Websites with higher PR (6, 7, 8) often make money by selling links to sites with lower PR. As Google states, if they are aware that sites are selling PR instead of just advertising space (how they can differ the two I can't say or if, ind eed, they can), both the buyer and seller may be penalized. The penalty may take the form of a lower position in SERPs and/or a downgrade of PR. Thus, we recommend that you do not buy links simply for a higher PR.

5. But I still would like to improve the PR of my site. What should I do?
First of all, sites don't have PR, pages do. (hence the name PageRank) Therefore, it is possible for an internal page to have a higher PR than the homepage. In order to get PR, the only way is to get links to it. Incoming backlink from a page with a higher PR is more valuable than incoming a backlink from a page with a lower PR. In addition, the PageRank that a link "gives" is spread out between the number of links on the page. For example, a backlink from a PR4 page with only two links on the page can be more valuable than a backlink from a PR7 page with fifty links on the page.

6. How many links would I need to get my homepage to PR7?
The answer to this question varies greatly between different sites. Sometimes a couple links from other PR7 or PR8 pages will do. On the other hand, you may need hundreds of backlinks from PR3 or PR4 pages.

7. I've acquired many backlinks to my site. Why isn't my PR improving?
There are many reasons why you may not be seeing the results. First of all, if you see PR5 for a page, the real PR may be PR5.0000 to PR5.9999. You have no way of knowing the exact PR of your site. Thus, you are simply not seeing the results. Secondly, Google might have done a PR algorithm update. Lastly, the PR of the pages that are giving you incoming backlinks might have changes, thus changing your PR as well.

8. How often do PR change?
Results may vary (a week to six months).

9. Why is my PR in the Google Directory different than my toolbar PR?
Google uses a different scale for measuring PageRank in the Google Directory.

10. Why is it so much harder to go from PR6 to PR7 than from PR5 to PR6?
Google Pa geRank value goes up logarithmically. (i.e. going from PR9 to PR10 may look like the same as going from PR1 to PR2, but is actually 1000 times more difficult). The exact logarithmic scale is unknown, but there has been speculation that it may be around 5. (i.e. going from PR2 to PR3 is 5 times more difficult than going from PR1 to PR2)

11. I just lost all my PR!
Don't panic just yet! Check to see if your PR is white-barred or grey-barred (white or grey in the PR ind icator). If it is white barred, then your PR will probably come back. However, if your PR is greyed, then it means that Google saw your site as having used unethical SEO techniques (e.g. selling/buying PR, keyword stuffing). Also, Google sees http://example.com/abc.htm and http://www.example.com/abc.htm as two different pages. In this case, the PR of the page is spread between these two UR Ls.

12. If PR is virtually useless, then why is it so expensive to "buy"?
Over the years there have been many misconceptions about PR. Sites with higher PR claim that PR is valuable so that they can make more money selling links. Gradually, the misconceptions quietly built up.

13. What's up with the PageRank formula I see on the Net?
You may have seen a formula to determine PR. I cannot say that the formula is untrue, but it's the implementation of the formula that is in question. Just remember, the Internet is NOT all about PageRank!

Tony Zhu is the owner of an <a target="_new" href="http://www.inawhim.com/">online business resource website</a>, InaWhim.com, the largest free resource center for the new and experienced home business owner. At InaWhim.com, you will find <a target="_new" href="http://www.inawhim.com/surveys.html">massive listings of paid survey companies</a>, products with free resell rights, exclusive quality articles, friendly community, and much more. Everything FREE!

1 ความคิดเห็น:

Matt Inertia กล่าวว่า...

Some good info but i have some corrections...

PR is still a big factor when ranking on Google. People who say it isnt are targeting low competition keywords where a title tag, h1 and a bit of content are enough for them to rank. There are indeed 100s of ranking factors but they are not all seen as equal. Some have more weight than others and PR has more weight than most!

In general high PR pages get crawled more frequently because they have more inbound links -- therefore Google bot is more likely to arrive at the page.

The google toolbar is not an accurate way to measure PR and it is available for other browsers as well as IE. It is only updated every 3/4 months and is massively manipulated by Google to tell us what we want to know. You can never know the 100% accurate value of a pages PR.


--"sites don't have PR, pages do. (hence the name PageRank)"
Its named PageRank after the inventor - Larry Page.

--"For example, a backlink from a PR4 page with only two links on the page can be more valuable than a backlink from a PR7 page with fifty links on the page."
I would much rather have a link on a PR7 page with 50 links than be the only link on a PR4 page. As you say... PR is logarithmic so you would still get more PR from the PR7 page.

--"How often do PR change?"
PR is changing all the time, minute by minute. For a particular page Google might re-calculate the PR every few days but Google will only update the tool bar every few months.