This plugin ensures that one you change a page or post’s URL, visitors (such as Google searchers) will still be able to find your content at the old URL.
What’s more the slugs are redirected in a way that lets the search engine know it can permanently change it’s records for that page.
This is an essential plugin because you will want to change things around sometimes while retaining your search engine juice.
- Official link: http://wordpress.org/extend/plugins/redirect–old–slugs/
- Author homepage: http://txfx.net/wordpress-plugins/redirect-old-slugs/