First lets create a new file and name it .htaccess (only if you don’t already have one), and ad the following lines at the very top:

Options +FollowSymlinks
RewriteEngine on
RewriteBase /

Now we are going to check the URL making sure the www. is always there otherwise we will redirect to the right format URL:

# redirect if not www
RewriteCond %{HTTP_HOST} !^(www)\.domain-name\.ie  

RewriteRule ^(.*)$ http://www.domain-name.ie/$1 [R=301,L]

Now lets redirect the index.php or .html to the main URL as this creates duplicated content as well:

#redirect index.php or htm to /
RewriteCond %{THE_REQUEST} ^GET\ .*/index\.(htm|html|php)\ HTTP  

RewriteRule ^(.*)index\.(htm|html|php)$ /$1 [R=301,L]

Depending on your server settings, sometimes the PHPSESSID get attached to the end of your URL, which will also created duplicated content, so there is a solution written in php that will check for the PHPSESSID query-string and if found, we will remove it and do a 301 Permanent Redirect to the same page but without it:

//remove session id from url  

if (!empty($_GET['PHPSESSID'])) {  

  $clean_uri = preg_replace('/?PHPSESSID=[^&]+/','',$_SERVER['REQUEST_URI']);  

  $clean_uri = preg_replace('/&PHPSESSID=[^&]+/','',$clean_uri );  

    header('HTTP/1.1 301 Moved Permanently');  

  header('Location: http://'.$_SERVER['HTTP_HOST'] . $clean_uri );  

    exit();  

}  

//

Please Note: The above solution is not part of the .htaccess file, but has to be added to a common include file available across the site.