How do I get my files indexed by the search engines after a redesign where file names have changed?

So you finally redesigned your circa-1997 website, and all the file names have changed. What should you do to ensure that the search engines index my new pages?

You should redirect all the old URLs to the new ones, via a 301-permanent redirect. If you’re on an apache server, this can be done via the .htaccess file. You may also want to submit a sitemap to Google with the new URLs.