Just a quick note that I have changed the URL of this blog to my personal domain - chrisbishop.co.uk which has been sitting politely waiting for some traffic - so please update your bookmarks.
But don't worry I wont leave my old readers behind! the blogspot domain http://chris-bishop.blogspot.com will 301 redirect to chrisbishop.co.uk - magic!
301 redirects play a major role in search engine optimisation. They enter into the equation in many different situations, but the 2 most common situations are:
All sites should redirect all URLs associated with their domain which do not start with "www" (i.e. "http://yourdomain.com") to the same pages on your their domain that start with "www" (i.e. "http://www.yourdomain.com"). This is referred to as a canonical redirect. The reason this is important is that search engines are not smart enough to tell if the non-www version of your domain is really a different site, or not, than the www version of your domain. And, if other people link to your site, you can't can't control whether or not they link to your site with a www or not.
Or you decide to move the content or moving to a completely new domain as I have done with chrisbishop.co.uk.
In either of these situations, you should use a 301 redirect. Other redirects are dangerous to use. Both the 302 redirect and the meta-refresh technique for performing redirects are potentially harmful to your site's ranking in the search engines. The 301 redirect is seen as a "permanent move" of the content, and the links to the page, to a new location and the search engine acts accordingly.
The 302 redirect and meta refresh are seen as "temporary moves" of the content.
Specifically, when a search engine sees a temporary redirect, the search engine continues to assume that the redirecting URL is the owner of the content. This means that all link credit associated with the redirecting page is associated with the redirecting page, and not the new page. In addition, you may get flagged as being a potential spammer, because in the past, spammers used temporary redirects to other people's sites as a way of stealing traffic from them.
When a search engine sees a permanent (301) redirect, it assumes that all credit for links to the redirecting page actually belong to the new page. This helps search engines transition to indexing the new page very quickly, and does not bear the potential stigma of association with past spammer tactics.
Google handles complex redirect situations as this very efficiently and will update its index very smoothly and quickly, and pass on all link credit from the old page to the new page. In our experience, Yahoo can take 6 to 8 months to correctly pass on all link credit for links to the old URL(s) to the new URL(s).
For that reason, you should only move URLs, or domains, when you really need to. Its important to not rely on these techniques unless you have to. But if you do, the 301 redirect is the tool of choice.
Fingers crossed Google will update my domain quickly and the authority of my blogspot domain will be correctly passed on.