HTTP status codes are crucial indicators used by servers to communicate the result of a client’s request. These codes are divided into five categories based on the nature of the response: informational, success, redirection, client errors, and server errors. Let’s explore each category to understand its purpose and the common status codes it includes.
Table of Contents
General Codes
| Status Code Range | Category | The server encountered an error or was unable to fulfill the request. |
|---|---|---|
| 1xx | Informational | The request has been received, and the process is continuing. |
| 2xx | Success | The request was successfully received, understood, and accepted. |
| 3xx | Redirection | Additional actions are needed to complete the request. |
| 4xx | Client Errors | The client made a mistake in the request. |
| 5xx | Server Errors | The server encountered an error or was unable to fulfil the request. |
1xx Informational
These codes indicate that the server has received the request and is continuing the process.
- 100 Continue: The client should continue with the request.
- 101 Switching Protocols: The server acknowledges the client’s request to change protocols.
2xx Success
These codes signify that the client’s request was successfully processed by the server.
- 200 OK: The request succeeded, and the server returned the requested resource.
- 201 Created: A new resource was successfully created as a result of the request.
- 202 Accepted: The request was accepted, but processing is not yet complete.
- 204 No Content: The server successfully processed the request but returned no content.
3xx Redirection
This category is used when further action is needed to complete the request.
- 301 Moved Permanently: The requested resource has been moved to a new URL permanently.
- 302 Found: The resource has been found under a different URL temporarily.
- 304 Not Modified: The client’s cached version of the resource is still up to date.
4xx Client Errors
Client error codes indicate that something went wrong with the request from the client side.
- 400 Bad Request: The request was invalid or cannot be processed by the server.
- 401 Unauthorized: Authentication is required and either failed or was not provided.
- 403 Forbidden: The client does not have permission to access the requested resource.
- 404 Not Found: The server cannot find the requested resource.
5xx Server Errors
These codes are used when something has gone wrong on the server side.
- 500 Internal Server Error: A generic error occurred on the server.
- 502 Bad Gateway: The server received an invalid response from an upstream server.
- 503 Service Unavailable: The server is temporarily unable to handle the request due to being overloaded or down for maintenance.
Conclusion
HTTP status codes are an essential part of web communication, providing insights into the success or failure of requests between clients and servers. Whether it’s a successful response like 200 OK or an error like 404 Not Found, understanding these codes helps in diagnosing issues and ensuring smoother communication between web applications. By familiarizing yourself with these codes, you can troubleshoot more effectively and build more reliable applications.