Importance of Page rank for website

Page Rank (often denoted by PR) is Google’s ranking software that calculates the relevance of a webpage with its content. Page Rank is a quantity (between 0 and 10) defined by Google that provides a rough estimate of the overall importance of a web page.

Page Rank is displayed as a green bar to the left of a webpage listing in the Google Directory, and also in the Google toolbar

The basic factor behind defining a page rank is the keywords

• If your keywords are Rare and Unique, then Page Rank doesn't matter.
• If your keywords are very Competitive, then Page Rank becomes very important

There are "over 200 SEO factors" that Google uses to rank pages in the Google search results (SERPs). There are certain google search engine optimization rules which effects the page rank they are

1. Positive ON-Page SEO Factors.

2. Negative ON-Page SEO Factors.

3. Positive OFF-Page SEO Factors.

4. Negative OFF-Page SEO Factors.

Some of these factors are listed below:
 POSITIVE ON-Page SEO Factors:

• Keyword
  • Keyword in URL: First word is best, second is second best, etc
  • Keyword in domain name: Same as in page-name-with-hyphens
  • Keyword in title tag: Title tag 10 - 60 characters, no special characters.
  • Keyword in description meta tag: less than 200 chars. Google no longer "relies" upon this tag, but will often use it.
  • Keyword in keyword meta tag: less than 10 words. Every word in this tag MUST appear somewhere in the body text. If not, it can be penalized for irrelevance. No single word should appear more than twice.
    If not, it may be considered spam. Google purportedly no longer uses this tag, but others do.
  • Keyword density in body text:5- 20% - (all keywords/ total words)
  • Individual keyword density: 1 - 6% - (each keyword/ total words)
  • Keyword in H1, H2 and H3: Use Hx font style tags appropriately
  • Keyword font size: "Strong is treated the same as bold, italic is treated the same as emphasis".
  • Keyword in alt text: Should describe graphic - Do NOT fill with spam
  • Keyword in links to site pages (anchor text): Links out anchor text use keyword
• NAVIGATION - INTERNAL LINKS
  • Link should contain keywords.
  • Use hyphenated filenames, but not long ones - two or three hyphens only.
  • Check that all Internal links are valid or not.
• NAVIGATION - OUTGOING LINKS
  • External link: Link only to good sites
  • Validate all links periodically
  • Less than 100 links out total
  • Avoid "Link Churn"
  • Outgoing link Anchor Text : Should be on topic, descriptive
• OTHER ON-Page Factors
• Smaller files are preferred, Try not to exceed 100K page size
• Use Hyphens in URL
• Freshness of Pages: Changes over time, Newer the better - Google likes fresh pages.
• Freshness of Links: Excellent for high-trust sites, May not be so good for newer, low-trust sites
• Frequency of Updates: Frequent updates are equal to frequent spidering that generates newer cache.
• URL length: Keep it minimized - use somewhat less than the 2,000 characters allowed by IE - less than 100 is good, less is even better

• OTHER ON-SITE Factors
  • Site Age:  Old is the best
  • Site Size - Google likes big sites
  • Age of page vs. age of site: Newer pages on an older site will get faster recognition

Negative ON-Page SEO Google Ranking Factors

• Text represented graphically is invisible to search engines.
• Too high keyword repetition (keyword stuffing) may get you the Over Optimization Penalty.
• Redirect through refresh metatags:  Don't immediately send your visitor to another page other than the one he/ she clicked on, using meta refresh.
• Keyword dilution: Targeting too many unrelated keywords on a page, which would detract from theming, and reduce the importance of your REALLY important keywords. 
• Flash page : Most SE spiders can't read Flash content Provide an HTML alternative, or experience lower SERP positioning.
• Use of frames should be avoided as SE has problems with frames.

• Excessive JavaScript should not be used.
• Invisible text Google advises against this.
• Gateway, doorway page Google advises against this.
• Duplicate content Google advises against this
• HTML code violations Google advises against this

POSITIVE OFF-Page SEO Google Ranking Factors

Incoming links :

• Based on the Number and Quality of links to you Google link reporting continues to display just a SMALL fraction of your actual backlinks, and they are NOT just greater than PR4 - they are mixed.
• Incoming links from high-ranking pages are better.
• Site Age - Old shows stability.
• Site Directory - Tree Structure.
• Complete - keywords in anchor text.
• PAGE METRICS - USER BEHAVIOR:
• Page traffic: trend of number of visitors.
• CTR: how often is the page clicked on.
• Time spent on page: Relatively long time, indicates relevance hit.
• If your website pages are bookmarked by user it is good for you.
• SITE METRICS- USER BEHAVIOR
• Site traffic: number of visitors are more its better.
• Time spent on domain: relatively long time indicates relevance hit.
• DOMAIN OWNER BEHAVIOR :
• Domain Registration Time: Register for 5 years, Google knows you are serious, register for 1 year, is it a throw-away domain?

NEGATIVE OFF-Page SEO Google Ranking Factors

• Traffic Buying is not suggested
• Old links are valued, new links are not.
• Zero links to you: You MUST have at least 1 (one) incoming link (back link) from some website somewhere, that Google is aware of, to REMAIN in the index.
• Google hates link-buying, because it corrupts their PR model in the worst way possible. Please check all these points before creating links:
  1. Does your page have links it really doesn't merit?
  2. Did you get tons of links in a short time period?
  3. Do you have links from high-PR, unrelated sites?
• Cloaking (practice of presenting different content or URLs to users and search engines.) should be avoided as Serving up different results based on user agent may cause your site to be perceived as deceptive and removed from the Google index.
• Links from bad neighborhoods: Google says that incoming links from bad sites can't hurt you, because you can't control them.

So we can say that the page rank is the function of page,

• Strong on page gives better page rank and strong off page is added advantage
• If off page is very strong and on page is bad then page rank will be very poor
• If on page is strong and off page is poor, then PR will not be that badly affected