Long ago, I wrote my post Blogging - The Directory and URL Structure.
Blogging - The Directory and URL Structure
http://fixtemplates.blogspot.com/2009/08/blogging-directory-and-url-structure.html
See the differences, between the title, and the URL? This difference bothers some blog owners, who want the Title and URL to match, word for word.
Just recently, I published a pair of brief static pages - A Test Of A Test, and The Test Of The Test. Note the URLs, please. Now, examine the pages.
http://fixtemplates.blogspot.com/p/a-test-of-test.html
http://fixtemplates.blogspot.com/p/the-test-of-test.html
See the difference between the page title, and URL?
Both the words "A" and "The", in page and post titles, are dropped from URLs - as interior words. Neither the leading "a " or "the " gets removed, however.
"a "and "the " remain, in any page or post URL. " a " and " the " are dropped, when rendering a title as a URL.
This is yet one more detail, that makes it a challenge to map Blogger URLs to various other website publishing platforms - when planning a blog migration, for instance.
If you re publish a post and end up with a URL change, use a custom redirect, to point the old URL to the new URL.