A 301 acts much like a link to a site pretty much.
The redirect tells the search engine to go from point A to point B.
A 302 to redirect is supposed to keep the original url but fetch content from page B or the new url.
302 Redirects are considered the best way to do a redirect for SEO
302 redirects make good sense for internal linking but not good when content is on different domains.
Regarding 307 redirects, they are used for pointing to an external resource that may move.
This may be used for redirecting your blog feed to feedburner. If Feedburner were to change your blog feed address would still remain the same.
You could use this for offsite calendars so you could 307 redirect to a Google Calendar and if a better calendar came out you could redirect to it instead.
Meta Refresh redirects is code in the head section of an html page. If it is a zero second delay it is treated as a 301 redirect. If it is any linger than zero seconds it is treated as a 302 redirect.
So this can be good sometimes particulary on a Yahoo store.
Javascript redirects can be done in many ways. We really don’t know exactly how search engines understand these.
The way you do this is to hide javascript redirect code and exclude it in your robots file.
Search engines do not have good visibility about what is going on so it is recommended to avoid this although the risk isn’t that high.
Checking your redirects to see if you did a good job
Go here to this tool: http://tx.cm/header-check
What matters when using this tool is the first lin that says “Status Code” and in regards to checking redirects, the location: header
If you get a 200 then your OK and it should then be followed by content.
If you get back a 300 series it should redirect OK but if you get a 400 series it cannot redirect the link.
The point of this tool is based on the premise that just because you see the redirect happening doesn’t mean the search engines do.
So seeing the 200 OK and 300 OK is a good thing but seeing 400 and 500 codes coming back when using this tool is not a good thing. Got it! Good!
All and all best practice when using any redirect is to use the rel=canonical tag for any link using redirect. Obviously this tage would go on the final link you want to be what the search engines see.
The rel=canonical as of late is becoming a popular standard used by most search engines to determine what a site wants the search engine to index as the main url in a redirect chain.
