One of WordPress’ strengths is its attention to SEO-related issues in its core files. One of those issues is the problem of having the home page of the blog indexed twice in the search engines; once under the actual address, http://domain-name.com/index.php, and the other as the plain domain name: http://domain-name.com. Note that this is a different problem than the trailing slash problem ( http://domain-name.com/ vs. http://domain-name.com ) which WordPress also takes care of.
WordPress handles the index.php problem by rewriting requests for http://domain-name.com/index.php to http://domain-name.com. All well and good, and beneficial for most sites.
But that rewriting/redirecting caused some problems on a site I was working on yesterday, and once I figured out how, it was a relatively easy fix. Read more