clean url with html file

We have site in plain html file and some time we want to use clean URLs or Pretty URLs for our site.
Clean URLs are in demand becasue of Seach Engine Optimiztion.

You can achive the Clean URLs. With not doing rework of building site.

Requirement:
Apache Server.
mod_rewrite engine need to on.

Create .htaccess file
and copy paste the following lines

Options +FollowSymLinks
RewriteEngine On

RewriteCond %{SCRIPT_FILENAME} !-d
RewriteCond %{SCRIPT_FILENAME} !-f

#code for About us Page
RewriteRule ^about-us(\d+)*$ ./about.html$1

Put this file into your root folder.

What this will do?

For example I want

www.example.com/about.html to look like www.example.com/about-us/