The page was found. Simple, straightforward and GOOD, this is a safe code.
206 Partial Content
The page was found, but something held up an element on the page from fully loading. This is not a concern.
The requested resource resides temporarily under a different URI.
This is the safest redirect for Search Engine Optimization, and there are no known penalties associated with using this redirect, while we recommend that you never use redirects, there are some instances that will require this type of redirect
When using any redirect from any page on your domain to another page on the same domain, you should ALWAYS use a 301
This directive used to pass PageRank from the old domain to the new one, but as some webmasters misuse this, there is evidence that suggests the PageRank will not pass from one domain to another. In most cases, this has been safe, but since January of 2006, during a Google Infrastructure change, many webmasters believe Google does not handle redirects properly, and some sites have had lost rankings due to them. It is recommended that if you can avoid redirects of any kind – DO SO.
Temporary Redirect. The page was moved to the new location, this is a temporary move, and it will return to a new location soon.
This is a dangerous redirect to use. If used on the same domain it can remove a site from some Search Engines. Evidence suggests that Google is the only Search Engine that has difficulty figuring out how to handle this redirect
It is sometimes used when moving an old domain to a new domain, as part of a name change or rebranding issue. It has the tendency to send all traffic from the old domain to the new domain, and in some cases, the new domain will retain the older domains rankings. As this is a bit more temperamental than the 301, the reverse is also possible, and scraper sites try to use this to hijack pages. 302 Hijacks only happen in Google. The webmaster uses this weakness in the Google Algorithm to steal rankings, and when combined with cloaking it can replace the hijacked page permanently. We recommend that you NEVER use this unless you are moving a website from an old domain to a new domain and only when the old domain still has rankings. You should seek the advice of a trained SEO for doing this.
304 Not Modified
You shouldn’t shouldn’t see this here – it only returns 304 when the client asks for a newer version of a URL.
307 Temporary Redirect
This is similar to a 302 redirect, the redirection is temporary and the existing URL should continue to be used.
400 Bad Request
The request could not be understood by the server due to malformed syntax.
The request requires user authentication a username and password are required to access. Password protected pages.
The server understood the request but is refusing to fulfill it. This is used to keep certain IP ranges from accessing any website.
404 Not Found
File Not Found. The page is missing, removed or lost. 404 errors can hurt rankings and need to be fixed.
The URL you were looking for is no longer available, and it was removed permanently. This is similar to 404 except this tells the Search Engine to remove the page. 410 means the page was intentionally removed and will never return, whereas a 404 error will tell the Search Engine that the page is missing or lost, and this may be a mistake the page may return.
500 Internal Server Error
The server has an error processing a request. Usually, this is from incorrect permission setting on a file or a more difficult problem that will require that you contact your web host.