This .htaccess rule is to remove the index.php file in CodeIgniter URLS.There is an example on how to remove this on the CodeIgniter User Guide but unfortunately it somehow doesn’t work.Anyway, here’s how to do it:

Put this code on your .htaccess file,changing “directory_on_where_is_your_CI” in which your CodeIgniter application resides.
If your CI application is in the root, just remove “directory_on_where_is_your_CI/” .

RewriteEngine On
RewriteBase /directory_on_where_is_your_CI/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /directory_on_where_is_your_CI/index.php/$1 [L]

Put the .htaccess file on the root if your CodeIgniter application,where the system/ folder resides.To test if it is working try removing the index.php file in the URL.

example.com/index.php/news/article/my_article

can be

example.com/news/article/my_article

but produces the same output.