The URL of this blog is currently "http://blogging.nitecruzr.net". As long as I publish the blog properly (as "blogging.nitecruzr.net"), I am allowed to advertise the blog using any combination of lower case and upper case letters, that I like. This blog can be accessed as "blogging.nitecruzr.net", "Blogging.Nitecruzr.Net", or even "BlOgGiNg.nitecruzr.net". We say that Blogger URLs are case insensitive.
Even with my readers allowed to use any combination of lower and uppercase letters, to access this blog, I don't want the search engines to index (and determine page rank) my blog using the exact URLs, as typed by each different reader. Even with this blog being addressed as "blogging.nitecruzr.net", "Blogging.Nitecruzr.Net", or even "BlOgGiNg.nitecruzr.net", the search engines index this blog as "blogging.nitecruzr.net".
To help this happen, Blogger uses the "canonical" tag, in the blog header.
The "canonical" tag is not unique to Google. It was developed as a standard in 2009, jointly, by Google, Microsoft, and Yahoo.
Every Blogger blog, which has a standard and up to date header, contains a "canonical" tag.
The "canonical" tag provides the base URL of the blog, in all lower case letters, so the search engines know how to ignore various syntax variations.more search engine generated traffic.
Look at the source for this blog home page, in the header. Note that you have to look at the online "source code" - not at the raw HTML, using the Template Editor!
Here's an excerpt of the header for this blog, with a few line breaks added - and some lines removed - to make it more readable.
<head> <meta content='IE=EmulateIE7' http-equiv='X-UA-Compatible'/> <meta content='width=1100' name='viewport'/> ... <link href='http://blogging.nitecruzr.net/favicon.ico' rel='icon' type='image/x-icon'/> <link href='http://blogging.nitecruzr.net/' rel='canonical'/> <link rel="alternate" type="application/atom+xml" title="The Real Blogger Status - Atom" href="http://blogging.nitecruzr.net/feeds/posts/default" /> <link rel="alternate" type="application/rss+xml" title="The Real Blogger Status - RSS" href="http://blogging.nitecruzr.net/feeds/posts/default?alt=rss" /> <link rel="service.post" type="application/atom+xml" title="The Real Blogger Status - Atom" href="http://www.blogger.com/feeds/24069595/posts/default" /> <link rel="EditURI" type="application/rsd+xml" title="RSD" href="http://www.blogger.com/rsd.g?blogID=24069595" /> <link rel="openid.server" href="http://www.blogger.com/openid-server.g" />
There it is.
<link href='http://blogging.nitecruzr.net/' rel='canonical'/>
My test blog, "Nitecruzr New Template Laboratory", is still published to "nitecruzrtestnew.blogspot.com".
<link href='http://nitecruzrtestnew.blogspot.com/' rel='canonical'/>
These records are essential, for blogs published to "blogspot.com", now that Blogger is aliasing our blogs using country code TLD URLs.
My test blog, for instance, published to "nitecruzrtestnew.blogspot.com", will be accessed as "nitecruzrtestnew.blogspot.in" in India - but the search engines, which observe the Canonical tag, will still index any links as "nitecruzrtestnew.blogspot.com".