Moving websites or deleting pages should not result in a loss of web traffic. Using 301 redirects will insure that you don’t.
People relocate from one residence to another all the time. So do websites. However, most of us would never move and leave no forwarding address. In reality, when you move a website and don’t direct search engines to the new content from the defunct pages, you are doing exactly that.
If your website has grown tired, or you have a new domain and a new site, you don’t have to loose all the search engine cred you’ve worked so hard to build up. That inbound link from an online professional directory—without a 301, will be gone. Just. Like. That. With a redirect, the search engine gods will know where to find you and will send your page visitor right along to you.
Google indexes and caches pages in their search engine to make browsing faster. New sites often aren’t indexed immediately and so for a period of time, Google will still direct site traffic to old pages which no longer exist. IF you tell search engines where to find the new pages which replace the old pages, you will in essence have left a forwarding address for them. So, when you update your website, and delete pages or add new pages or even create a new site to replace an old site, be sure to have your webmaster create 301 redirects for the pages which are disappearing and being removed the web.
If you don’t do this, people coming to find your site and pages will get a big fat 404 error. To translate from geek speak, a 404 is the Interwebs’ way of saying, “Sorry, wrong number,” Or “Recipient moved, no longer at this address.”
Photo credit: flickr creative commons user Pheezy