URL redirect through .htaccess file

URL rewrite helps you to hide your extension name or show different extension name like index.php can be displayed as index.html or only index or home etc.
The following code will rewrite anyfile.php to anyfile.html

RewriteEngine on
RewriteRule ^(.*)\.html$ $1.php

The following code will rewrite index.php to index

RewriteEngine on
RewriteRule ^index index.php

Few Example to create SEO friendly URL.

1. Rewrite product.php?id=1 to product-1.html

RewriteEngine on
RewriteRule ^product-([0-9]+)\.html$ product.php?id=$1

2. Rewrite product.php?id=12 to product/cat/12.html

RewriteEngine on
RewriteRule ^product/([a-zA-Z0-9_-]+)/([0-9]+)\.html$ product.php?id=$2

3. Rewrite domain.com/member.php?username=arup to domain.com/susil

RewriteEngine on
RewriteRule ^([a-zA-Z0-9_-]+)$ user.php?username=$1
RewriteRule ^([a-zA-Z0-9_-]+)/$ user.php?username=$1

4. Rewrite domain.com/users.php?id=username&page=2 to domain.com/username/2

RewriteEngine on
RewriteRule ^([a-zA-Z0-9_-]+)/([0-9]+)$ users.php?user=$1&page=$2
RewriteRule ^([a-zA-Z0-9_-]+)/([0-9]+)/$ users.php?user=$1&page=$2