Glossary of HTTP Response Codes

Glossary of Hypertext Transfer Protocol (HTTP) Response Codes

Hypertext Transfer Protocol (HTTP) response codes are three-digit numbers that provide information about the status of a web page or request. These codes help in communication between web servers and browsers, ensuring smooth browsing experiences for users. 

Classes of HTTP response codes

There are five classes of HTTP response codes, each with a range of codes:

Informational (1xx): These are purely informational and rarely seen in practice.

Success (2xx): These codes indicate that the request was successfully received, understood, and accepted.

Redirection (3xx): These codes indicate that the client needs to take additional action to complete the request.

Client Error (4xx): These codes indicate that there was an error on the client’s side, such as an invalid request or unauthorized access.

Server Error (5xx): These codes indicate that there was an error on the server’s side, such as an internal server error or service unavailability.

Within each class, there are multiple specific codes. The exact number of codes in use may vary over time as new codes are introduced or deprecated. However, there are over 50 defined HTTP response codes but you don’t need to know them all. 

Commonly used HTTP response codes

You have likely seen some of these and maybe your heart stopped a beat. But, don’t worry. Knowing what some of these codes mean can help start the troubleshooting process and knowing when to contact your hosting provider or when it is an error you have created (we’re all human and have done things without giving it too much thought! I’ve been there.) and guide you in taking the next steps to correcting it!

Here are the most commonly used HTTP response codes that you may come across: 

  1. 200 OK: Everything is working fine, and the requested web page has been successfully delivered to your browser. You likely won’t see this but it is nice to know when things are okay!
  2. 301 Moved Permanently: The requested web page has been permanently moved to a new location. Your browser will automatically be redirected to the new address.
  3. 302 Found: The requested web page has been temporarily moved to a different location. Your browser will be redirected, but the original address may be used again in the future.
  4. 400 Bad Request: Oops! Your browser sent an invalid request to the web server, which couldn’t understand it. Check your URL or the data you’re trying to send.
  5. 401 Unauthorized: Uh-oh! The web server requires authentication or login credentials before granting access to the requested page. Please provide the necessary credentials.
  6. 403 Forbidden: Sorry, but you don’t have permission to access the requested web page. It’s like being denied entry to a members-only area.
  7. 404 Not Found: Oh no! The web page you’re looking for couldn’t be found. It might have been moved, deleted, or simply doesn’t exist.
  8. 500 Internal Server Error: Something went wrong on the web server’s side while processing your request. Don’t worry; it’s not your fault. The server needs some fixing.
  9. 502 Bad Gateway: When the server acting as a gateway receives an invalid response from an upstream server, it returns this code. It’s like a relay runner dropping the baton.
  10. 503 Service Unavailable: The web server is temporarily unavailable, usually due to maintenance or high traffic. Try again later, and it should be back up and running.
  11. 504 Gateway Timeout: The server acting as a gateway didn’t receive a timely response from an upstream server. It’s as if the gateway gave up waiting for a response.

HTTP response codes play a vital role in maintaining a smooth browsing experience for users. They provide helpful feedback about the status of web pages and requests. From letting you know a page has moved to informing you about errors or server issues, these codes keep the lines of communication open between your browser and web servers. 

So, next time you encounter an HTTP response code, don’t fret and remember that it’s there to guide you and help you navigate the boundless digital universe of the internet with ease.

June 27, 2023

Written by Digital Marketing by Design

Digital Marketing by Design is a virtual support business specializing in website design, digital marketing, technical suppport and administrative assistance.


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