Before we get into explaining this plugin we need to address the problem it fixes.
When you create a post on your site it will have a URL or page address (depending on your permalink set up it will look different but this issue is the same) and after you create that post and address you need to change it for one reason or another, say for example you misspell a word in the title, but the problem is you have already added this address to twitter, or Digg or told someone to look at it via email.
If you make a change to the address this would mean that when someone clicks the old link they will instead be presented with an error page because it no longer exists. This error page is called a 404 Page and means, quite literally, that the page does not exist.
This is where the Redirection plugin comes in. Activating Redirection means that the configuration for adding a redirect to the original page to the new address is automatic. You have to do nothing (aside maybe from not making spelling erros in the first place!) and the redirect it puts in place is called a 301 redirect.
A 301 redirect is very important in internet terms because it is the accepted format for search engines as well, who will see this code and any ranking, links or PageRank you had assigned to the page will follow it and maintain its integrity.
All done automatically. The plguin also offers a range of other features as well that can be used for analysis and tracking of redirects and setup etc, incredibly useful and powerful.
Author: John Godley
Download the WordPress Redirection plugin.