The HyperText Transfer Protocol (HTTP) 308 Permanent Redirect redirect status response code indicates that the resource requested has been definitively moved to the URL given by the Location headers. A browser redirects to this page and search engines update their links to the resource (in 'SEO-speak', it is said that the 'link-juice' is sent to the new URL).
The request method and the body will not be altered, whereas 301 may incorrectly sometimes be changed to a GET method.
Note: Some Web applications may use the 308 Permanent Redirect in a non-standard way and for other purposes. For example, Google Drive uses a 308 Resume Incomplete response to indicate to the client when an incomplete upload stalled. (See Perform a resumable download on Google Drive documentation.)