Technically speaking, a 301-redirect returns the HTTP status code 301 Moved Permanently.
The webserver answers the client requesting the page, for example the Google-Bot or a web browser, with the HTTP status code 301 if the requested resource (for example a URL, a HTML document) has been permanently moved and is now available on a new URL. By returning the 301 status code, the webserver redirects all requests for a certain source-URL to the new target-URL.
For the user as well as clients, the 301-redirect has the advantage of not sending them to a 404 error page, but redirecting them to the (requested) resource (the URL). A 301-redirect is almost invisible to the user, as only the URL in the address-bar of their web browser will change.
Table of Contents
Easily explained: The way of a 301-redirect
In the following chart you can see the technical steps of what happenes during a 301-redirect.
What happens during a 301-redirect?
- The Google-Bot would like to get the file “abc.html” from the domain “domain.com”
- The Google-Bot sends a request to the webserver of the domain “domain.com” and asks for the file “abc.html”
- The webserver notices that the file “abc.html” does not exist anymore on the URL “domain.de/abc.html”. In addition, the webserver realises that there is an existing 301-redirect for the file “abc.html” to “xyz.html”
- The webserver returns the HTTP status code 301 (Moved Permanently) to the Google-Bot and points to the new URL, “domain.de/xyz.html”
- The Google-Bot understands that the content of the file “domain.de/abc.html” can now be found at the URL “domain.de/xyz.html”. From now on, when trying to access the file “domain.de/abc.html”, a user will be redirected automatically to “domain.de/xyz.html”
When should I use a 301-redirect?
Having a 301-redirect is always useful when URL-structures of a website or even the entire domain name are changed. They are also useful when two websites are merged together, or when the content of a website can be accessed through two different URLs.
301-redirects do not have a high dampening factor
A redirect using the HTTP status code 301 (Moved Permanently) does not, according to Matt Cutts, Head of Googles Webspam-Team, dissipate more PageRank than links do. That is why redirecting internal and external links using a 301-redirect is a good idea.
- The video from Matt Cutts on this topic can be found at https://www.youtube.com/watch?v=Filv4pP-1nw
Additional information on this topic:
Video explanation on this topic
Is there a limit on how many 301 redirects one can use in a row without getting a crawling problem?