Over time, your blog evolves (hopefully). This means category names change, posts are updated, files move or subdirectories are deleted. What happens when someone clicks a link to a post or file that is no longer there?
They get a 404 Error.
Even with a Custom 404 Error Page, you didn’t deliver the content they thought they were getting. So they might leave.
And if you published that link in a number of places (as you should be doing), you now have *deadlinks* that aren’t getting your visitors to the content you promised them.
You can stop the leaks, plug the holes and deliver the content you promised, no matter where it moved to, even a new domain.
Watch the video and then go grab the Redirection Plugin and start plugging up the holes that evolution leaves behind.