what is canonicalization? Problems with it...

Canonicalization and Problems with it...

For SEOs, canonicalization refers to individual web pages that can be loaded from multiple URLs. This is a problem because when multiple pages have the same content but different URLs, links that are intended to go to the same page get split up among multiple URLs. This means that the popularity of the pages gets split up. Unfortunately for web developers, this happens far too often because the default settings for web servers create this problem. The following lists show the most common canonicalization errors that can be produced when using the default settings on the two most common web servers:

Apache web server:

http://www.example.com/
http://www.example.com/index.html
http:/example.com/
http://example.com/index.html

Microsoft Internet Information Services (IIS):

http://www.example.com/
http://www.example.com/default.asp (or .aspx depending on the version)
http://example.com/
http://example.com/default.asp (or .aspx)
or any combination with different capitalization.

Each of these URLs spreads out the value of inbound links to the homepage. This means that if the homepage has multiple links to these various URLs, the major search engines only give them credit separately, not in a combined manner.


Luckily for SEOs, web developers developed methods for redirection so that URLs can be changed and combined. Two primary types of server redirects exist: 301 redirects and 302 redirects:

A 301 indicates an HTTP status code of �Moved Permanently."
A 302 indicates a redirect that is temporary

You can read easily understand 301 Redirect from the image given below:

read more at : http://www.seomoz.org/learn-seo/canonicalization