Whenever a search engine or user makes a request to gain access to a web server, a HTTP response is returned. HTTP stands for HyperText Transfer Protocol and these statuses report the success of the requests. There are six main unique HTTP status codes, each containing three digits, which can be returned.

The first digit of the status code, which will be 1-5, helps categorise the HTTP responses into which type of response it is. The categories are:

  • 100 – The web server has received your request and is still processing the request
  • 200 – The web server has received your request and processing has been a success
  • 300 – The web server has received your request but an additional step needs to be completed before the process is complete
  • 400 – The request was made by the user but the page they are trying to access is not found on the web server
  • 500 – The request was made by the user but due to a server error the request was unable to be completed

The most important status codes in terms of SEO are:

200 OK

This status code means that your request was successful; this is the HTTP code for all successfully loaded pages

301 Moved Permanently

This status code means that the page you have requested has been permanently moved to a new URL. In SEO this status code should be used when a URL needs to be redirected to a new URL i.e. if you no longer sell a specific product, instead of deleting the page you should redirect it to the category/subcategory page above it.

302 Found

The 302 status code is similar to the 301 redirect but it is temporary, this could be used whilst you are doing maintenance on a specific page but don’t want the page to 404. 302 redirects should be used sparingly and should not be used for permanent redirections as it does not tell search engine bots that a page has moved permanently, in turn this will not give the 302 redirected pages the ranking benefits that a permanent 301 redirect would receive.

404 File Not Found

The 404 error status code means that the web server has not found anything in its database that matches the request URL, this will occur every time a page is removed from the site without being correctly 301 redirected to another relevant page or if the user has misspelt the URL path. It is best practise and good for user experience for you to create a custom error page that explains to the user that the file/page they are looking for cannot be found and/or has been removed. This page should give the user the ability to search for a similar page, go back to the homepage or have a clear navigation where they may find what they were originally looking for. Avoid 301 redirecting pages that 404 to the homepage, it is bad practise and it makes more sense to show a customer a 404 page so they know the page doesn’t exist and they won’t request it again.

410 Gone

The 410 status code is similar to the 404 error code but it only appears when a user searches for a page that once existed whereas 404 errors appear when the user searches for something that has never existed and the server is unable to find such as www.weareinfront.com/abc. The 410 status code tells search engine bots to remove the URL from their crawl.

503 Service Unavailable

The 503 status code should only be used when the server is temporary unable to deal with the request or the server is going through maintenance. This status code tells search engine bots that although the site is down it is only temporary.