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Complete Guide HTTP Status Codes

HTTP Status Codes - Complete Guide for Developers

HTTP status codes are essential communication tools between web servers and clients, providing vital information about the outcome of a client's request. These three-digit numerical codes categorize responses into different groups, each conveying specific information about the status of the request. Understanding these status codes is crucial for developers, as they help diagnose and troubleshoot issues that occur during web interactions.

What Exactly Are HTTP Status Codes?

HTTP status codes are standardized numerical codes served by a web server in response to a client's request made to the server. These codes convey information about the success or failure of the request and are grouped into different classes based on the first digit of the status code.

Informational Responses - 1xx

1xx status codes are informational responses indicating that the client's request has been received and the server is continuing the process. These provisional responses are used to inform the client that the server has received the request and is still processing it. Common 1xx status codes include:

  1. 100 - Continue Concept: Indicates that the initial part of the request has been received successfully by the server, allowing the client to proceed with the rest of the request. This code informs the developer that the server is ready for the client to send the remainder of the request.

  2. 101 - Switching Protocols Concept: It signifies that the server agrees to the client's request to switch protocols and that the protocol change is happening. Developers should expect subsequent communication to occur using the newly requested protocol.

  3. 102 - Processing Concept: This status indicates that the server has received and is processing the request but hasn't completed it yet. It's helpful for developers as it informs them that the server has acknowledged the request and is actively working on it.

Success Responses - 2xx

2xx status codes indicate that the client's request was successfully received, understood, and accepted. These codes signify that the requested action has been successfully received, understood, and accepted. Examples of 2xx status codes include:

  1. 200 - OK Concept: Indicates that the request was successful and that the server has fulfilled the request made by the client. This status assures developers that their request was processed correctly.

  2. 201 - Created Concept: Confirms that the request has been successfully fulfilled and has resulted in the creation of a new resource as requested by the client. Developers can use this response to confirm the successful creation of resources.

  3. 204 - No Content Concept: It indicates that the server has successfully processed the request but does not need to return any content. Developers can utilize this status in scenarios where a response body isn't necessary.

Redirection Messages - 3xx

3xx status codes inform the client that further action needs to be taken to complete the request. These status codes are used for redirection. Some common 3xx status codes are:

  1. 301 - Moved Permanently Concept: Tells developers that the requested resource has been permanently moved to a new location. It's crucial for developers to update their links to the new location to avoid broken links.

  2. 302 - Found Concept: Informs developers that the requested resource is temporarily located elsewhere. It suggests that the client should continue using the original URL or the new one, depending on the context.

  3. 303 - See Other Concept: It indicates to developers that the response to the request can be found at a different URI and should be retrieved using a GET method. This is often used in redirection after a POST request.

Client Error Responses - 4xx

4xx status codes indicate that there was an error on the client's side. These errors often stem from the client’s request and can be related to incorrect syntax or the unavailability of a resource. Examples of 4xx status codes include:

  1. 400 - Bad Request Concept: Indicates that the server cannot process the request due to a client error, often due to malformed syntax or invalid parameters in the request. Developers need to review and fix the client's request.

  2. 403 - Forbidden Concept: Tells developers that the server understood the request but refuses to authorize it. This can happen due to lack of permissions or authentication issues.

  3. 404 - Not Found Concept: Indicates that the requested resource is not available on the server. It's essential for developers to handle this response by providing appropriate feedback to users or locating alternative resources.

Server Error Responses - 5xx

5xx status codes indicate that the server failed to fulfill a valid request from the client due to an error on the server's end. These errors generally indicate problems with the server or its configuration. Some common 5xx status codes are:

  1. 500 - Internal Server Error Concept: Informs developers that something went wrong on the server's end while processing the request, without specifying the exact cause. It suggests an issue within the server that needs to be addressed.

  2. 503 - Service Unavailable Concept: Notifies developers that the server is currently unable to handle the request due to maintenance or overloading. This status is temporary and advises developers to try again later.

  3. 504 - Gateway Timeout Concept: This status indicates that the server acting as a gateway or proxy did not receive a timely response from an upstream server. It suggests that developers check the communication between servers or services.


Stepping through the world of HTTP status codes might feel like exploring a new city. Each code, like a street, guides us towards a better understanding of how the digital world communicates. From the informational avenues of 1xx to the bustling success boulevards of 2xx, each provides valuable insights into the complex web infrastructure.

As we journey into the redirection roundabouts of 3xx, we learn the art of navigational flexibility. The erroneous alleyways of 4xx teach us the humbling lessons of resilience and troubleshooting. And inevitably, when we encounter the server-side slip roads of 5xx, it reminds us that even the strongest systems have their rainy days.

Now that we've toured the city of status codes together, I hope you feel more confident navigating its lanes and byways. Remember, each code is more than a number; it's a conversation between server and client, a subtle dance of request and response that keeps our online worlds buzzing.


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