301 redirects are important if you are moving or relocating a website or webpage that has already got traffic and/or PageRank.
By using a 301 redirect search engines, well Google definately, will see the redirect as a permanent move and all page rank from the old URL will filter through to the new url.
Please note that although 301 and 302 redirects are more or less identical, a 302 is intended to be used as a temporary redirect. Search engines do not treat 302 the same as 301 – 301 is what you need.
There are lots of different way to go about it but the two techniques that I tend to use are:
Redirect with PHP
Redirect in Apache
Redirect 301 / http://new.url.com/
If you want to check you redirect to make sure it’s using 301 and not 302 (especially if this has been undertaken by you web development company) then the Search Engine Friendly Redirect Checker tool can help.
Remember use 301 and not 302.