Hello, anybody can tell me what's the different between 301 redirection and 302 redirection ? Thanks!
301 redirection is used for permanently moved page while 302 is used for temporary. 301 redirection tells search bots to replace old url with new url. Search engine bots won't make any replacement and would keep looking for old url when 302 redirection is used.
@TechMaster: Excellent explanation. From SEO point of view you should always use 301. When you use a 302 redirect both search engine bots and browser are told to use a different URL 'temporarily'. This can be used by CDNs to redirect to a nearest data point.
3xx - Redirection The client browser must take more action to fulfill the request. For example, the browser may have to request a different page on the server or repeat the request by using a proxy server. * 301 - Moved Permanently * 302 - Object moved. source: h**p://support.microsoft.com/kb/318380
About 9 times out of 10 you will want to use a 301 redirect. There are not many reasons to use a 302. Using a 301 can push some of the PR juice to the URL/domain it points to where 302 doesn't send any PR juice.
301 redirects, as others have said, are Permanently Moved redirects. It causes the engines to do several things. It tells the engines to give the target URL of the redirect credit for all inbound links to the redirected URL and at Google, at least, to replace the old URL with the new URL in their index (Yahoo! doesn't seem to necessarily do this. I've been waiting 4+ months and they are still showing old URLs). 301 redirects, because they pass credit for inbound links, also pass Page Rank (PR) from the old URL to the new URL. 302 redirects are Temporarily Moved redirects. They do NOT pass credit for inbound links to the target URL. The do NOT pass PR to the target URLs. They do NOT cause the engine to replace the redirected URL with the target URL in the index. Although they WILL cause the content located at the target URL to be indexed under the redirected URL.