According to the Apache site
.htaccess files (or “distributed configuration files”) provide a way to make configurative changes on a per-directory basis. A file containing one or more configuration directives is placed in a particular document directory, and the directives are applied to that directory and all sub-directories thereof.
Apache goes on to recommend against the use of .htaccess under most cases. These “most cases” are where quite a few shared host Joomla! sites live. In my opinion, the .htaccess file is still one of the best safeguards against hackers launching attacks on your site, though it can become bloated and affect performance.
The .htaccess information has been provided by and used with the permission of Mr. ...