The ultimate Magento SEO .htaccess rewrite rule set

.htaccess

# Grab the protocol being used

    RewriteCond  %{HTTPS} =on
    RewriteRule ^(.+)$ - [env=ps:https]
    RewriteCond  %{HTTPS} !=on
    RewriteRule ^(.+)$ - [env=ps:http]

# Force WWW

    RewriteCond %{HTTP_HOST} !^www\.
    RewriteRule ^(.*)$ %{ENV:ps}://www.%{HTTP_HOST}/$1 [R=301,L]

# Remove index.php from URLs

    RewriteCond %{REQUEST_URI} ^/index.php/?
    RewriteRule ^index.php/?(.*)$ %{ENV:ps}://%{HTTP_HOST}/$1 [R=301,L]

# Force trailing slashes

    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_URI} !.html
    RewriteCond %{REQUEST_URI} !(.*)/$
    RewriteRule ^(.*)$ %{ENV:ps}://%{HTTP_HOST}/$1/ [R=301,L]