I recently did a couple of tutorials on configuring htaccess files specifically for Drupal to enable clean URLs (since Drupal is a dynamic content management system "CMS" it's URL's would otherwise have = and ? characters in them) and also to force or restrict the www protocall from a URL.

If you're a "normal" website owner with a site that isn't dynamic then it will already have clean URL's so the first tip doesn't help you. The second htaccess tip however, is very valuable indeed! Forcing or restricting the www from the beginning of all of your URL's will help your search engine rank because it will keep search engines from "double indexing" your site. You see, if half of your customers and friends link to http://www.yoursite.com and the other half link to the shorter http://yoursite.com then your link value gets cut in half! This is a very important concept because Google, and many other search engines determine your site's worth based on how many incoming links it has. It's like voting on the web, and you want every vot for your site to count!

By updating or adding a file to the root directory of your website called .htaccess with the following lines of code you will be creating a switch that tells web browsers and search engines STOP! My site always includes www. or STOP! My site never includes www and everyone will be a lot happier. If this is something you want done for you then I would be happy to migrate your site FREE OF CHARGE over to my hosting company, Sustainable Online Solutions, and set up the .htaccess file for you! Our hosting rates can be found here http://www.sustainableonlinesolutions.net and you can reach us at (800) 280-1364 for sales and support (press 1 at the menu) or mail us a request.

Note, it doesn't matter whether your visitors type the www or not, this code will override what they typed and "redirect" them to the version you choose. It is also worth mentioning that the .htaccess file can be easily missplaced on Mac computers and Windows computers that aren't set up to display full file extensions. For this reason I recommend coppying the following code and pasting it into a text editor like Notepad on PC or TextEdit on Mac and then saving it as htaccess.html here are the full instructions:

1. Copy the following code
2. Paste it into a text editor (MS Word won't work, use Notepad or TextEdit)
3. Change the URL in the code from example.com and www.example.com to your URL
4. Save As htaccess.html (you will rename it once it's posted online, this just keeps it from getting lost on your computer and it also helps to ensure that when you FTP it the permissions are set correctly)
5. Upload it to the root directory of your website (where index.html or default.html are)
6. Rename the file .htaccess

That's it! You are now on your way to realizing SEO benefits site wide :) 

# Various rewrite rules.
  RewriteEngine on

  # If your site can be accessed both with and without the 'www.' prefix, you
  # can use one of the following settings to redirect users to your preferred
  # URL, either WITH or WITHOUT the 'www.' prefix. Choose ONLY one option:
  #
  # To redirect all users to access the site WITH the 'www.' prefix,
  # (http://example.com/... will be redirected to http://www.example.com/...)
  # adapt and uncomment the following:
  RewriteCond %{HTTP_HOST} ^example\.com$ [NC]
  RewriteRule ^(.*)$ http://www.example.com/$1 [L,R=301]
  #
  # To redirect all users to access the site WITHOUT the 'www.' prefix,
  # (http://www.example.com/... will be redirected to http://example.com/...)
  # uncomment and adapt the following:
  # RewriteCond %{HTTP_HOST} ^www\.example\.com$ [NC]
  # RewriteRule ^(.*)$ http://example.com/$1 [L,R=301]

  # Modify the RewriteBase if you are using Drupal in a subdirectory or in a
  # VirtualDocumentRoot and the rewrite rules are not working properly.
  # For example if your site is at http://example.com/drupal uncomment and
  # modify the following line:
  # RewriteBase /drupal
  #
  # If your site is running in a VirtualDocumentRoot at http://example.com/,
  # uncomment the following line:
  # RewriteBase /

  # Rewrite URLs of the form 'index.php?q=x'.
  RewriteCond %{REQUEST_FILENAME} !-f
  RewriteCond %{REQUEST_FILENAME} !-d
  RewriteRule ^(.*)$ index.php?q=$1 [L,QSA]

If your site is in a directory just add the line RewriteBase / directly below # Rewrite URLs of the form 'index.php?q=x'. and it will work or leave a comment on this post and the community and I will do our best to help you out :)