Perfect 301 URL Redirection is the one of the biggest factor affecting the ranking of your site and a major factor to be considered in On Page SEO. Redirect is most efficient way to permanently move your site from one site to another. I think am not wrong if I say 301 status code means your webpage has permanently moves to a new location.
The head of web spam at Google Matt Cutts says: “The amount of Page Rank that dissipates through a 301 is currently identical to the amount of Page Rank that dissipates through a link” well, that’s worth sharing. 301 is automatically noticed by Google, So let Googlebot find it in its own time
Why you need to use 301 Redirect
301 Redirect is used when you want to merge two sites. Assume your last domain is expired & you want to redirect expired domain to new location.
When you have moved old website to new
The advantages of using 301 redirects over rel=”canonical”
We use 301 to avoid 404 error pages file not found. It is a direct instruction for redirecting pages through .htaccess file or webmaster tools while rel canonical is used to avoid duplicate contents.
For more information you can see Matt Cutts video here.
Suggestions when you use 301 Redirect:
First of all try to redirect section or directory then check is it works properly if okay then moves your whole contents.
Adam, a web maintenance expert suggested that avoid using single redirection to redirect your all traffic from old domain to new web page. If you do this definitely you can avoid 404 errors, but it will not help you protect your site ranking. If your want to redirect large site & want to avoid page-to-page redirection then make sure every page of old site which you want to move to new page it should have identical content.
If you are going to use the Change of Address tool, then you need to verify the owner of both new & old websites by search engine.
When you complete 301 redirect then add your new website to webmaster tools account & confirm your ownership of new website.
Submit your sitemap if you want Google will find your site that shows the listing of new site url. You need not to update your website URLs in existing listings or you can get your listings updated from local citation building service providers.
When you complete your 301 redirection then use webmaster tool to check everything is ok.