URL Canonicalization - .htaccess (Apache)

rewriteengine on

#Canonicalization
RewriteCond %{HTTP_HOST} ^domain\.com [NC]
RewriteRule ^(.*) http://www.domain.com/$1 [R=301,L]

#URL redirection - Making better URLs
RewriteRule   this-url-is-better   index.php?id=bad-url-12

#Custom Error Page
Error Document 404 /404.php