A website is always evolving and changing. No doubt you will eventually need to move pages or change the file extensions of your pages.
For example, your page that was on http://www.example.com/mypage.html might need to be moved to http://www.example.com/apple/mypage.html
Or http://www.example.com/mypage.html might change to http://www.example.com/mypage.php as you put switch to using PHP server-side scripting.
But you have other people currently linking to your old pages and search engines still have your old pages listed in their index. How do you get all this traffic to be directed to your new page and hopefully not loose any SEO ranking?
According to the article "How to Redirect a Webpage" it says "301 redirect is the most efficient and Search Engine Friendly method for webpage redirection. It's not that hard to implement and it should preserve your search engine rankings for that particular page." The 301 return code tells the browser that "page has moved permanently".
There are many server-side methods for performing the 301 redirection. Steven Hargove has a good tutorial here of the various methods depending on whether you are using PHP, ASP, Coldfusion, or others for your backend technology.
If you are on Apache web server, there are a few commands that you can use to perform a redirection. They include "redirect", "redirectmatch", and "mod_rewrite". Here are some examples. If you just moved one or a few pages, then the redirect command may be the simplest as described here. See also the section "Using .htaccess for redirection" in Wikipedia.
Your page often can be access with or without the www. For example, http://www.example.com/mypage.html and http://example.com/mypage.html both works. To consolidate their listing in search engine index, webmasters sometimes want all traffic coming to http://example.com to be redirected to http://www.example.com
This can again be done using the Apache mod_rewrite. Some example tutorials linked here ...
In the above section we saw the various ways of redirecting the traffic of a moved page. However many of those techniques relies on your having to put up the page at the old location. If you are on a Linux webhost that has mod_rewrite ability (and most shared webhost does), then writing a few links of code in the .htaccess file is a more powerful and more flexible way performing the 301 redirection without needing to put up extra pages.
Here are some tutorials on how to use mod_rewrite in your .htaccess file to perform a 301 redirection ...
I do recommend the use of the [NC] in the .htaccess code as it makes the RewriteCond case insensitive. And depending on your webhost configuration, you may need to add Options +FollowSymLinks as mentioned here and here.
As mentioned by Brain Bonini's article and Jennifer Kyrnin's article, you do not want to use meta refresh to perform redirection.
