Be Consistent With Link URLs

When setting up links always use the same URL.

What does that mean? I can hear some of you say, "Of course I'm not going to use different URLs for the same link."

There are a number of different ways the same URL can be written. Let's look at the URL for a home page, for example the page at: http://www.zd85.com/index.html

The above is an absolute link. Links from other pages in the root directory can be relative, such as:

index.html

And a link from a subfolder can be: ../index.html

These are relative links, meaning that they are relative to the page on which they are located.

Absolute links for a home page also have a number of valid variations:

http://zd85.com/
http://zd85.com/index.html
http://www.zd85.com/
http://www.zd85.com/index.html

Google has suggested that all links to a page should have the exact same URL. Even internal links should be written as absolute links, using the exact same URL as you use for links from external sources. That way their spider will not classify ../index.html, http://zd85.com/index.html and http://www.zd85.com/index.html/ as three different pages.