An HTTP status code returned by the server to the browser (often accomplished through an entry in the .htaccess file) to indicate that the requested resource has moved to a new location and that the move is permanent.
A 301 redirect helps search engines find pages or resources when the URL has changed, and allows link equity to pass through to the new URL. 301 redirects also automatically send visitors to the new location, ideally allowing them to find content that has moved without experiencing a 404 error.
See also: .htaccess, Redirect