Hello,
Actually i want to redirect my url through cloaking and i want to know that how it works in htaccess ?
I want to do when user write some Url and it should open some different Url content …
It’s called ‘URL rewriting’. Search Google for ‘htaccess url rewrite’ and you’ll find tons of tutorials 
Basically, what it does is that you specify rules and, based on those rules, you redirect a URL to a PHP file.
So you could write a rule to redirect all urls that starts with /categories/ to a php file name ‘categories.php’. This PHP file could take what’s in the URL after ‘/categories/’ and find information based on that.
For example, lets say that you have a URL like ‘/categories/shoes’. Apache will ‘redirect’ the URL to your PHP script 'categories.php. This PHP script will be able to extract the ‘shoes’ part. Based on this, it could query a database and display all shoes available on the page.