What are HTTP status codes? Explanation of the basic concept of the response state of web communication

Explanation of IT Terms

What are HTTP status codes?

HTTP, or Hypertext Transfer Protocol, is the foundation of data communication for the World Wide Web. When you visit a website or interact with web services, HTTP enables your browser or client application to communicate with the server in a standardized manner. As part of this communication, HTTP status codes are used to indicate the status or outcome of a request.

A HTTP status code is a three-digit numeric value that is included in the response sent by the server to the client. These codes provide valuable information about the outcome of the request, allowing the client to understand what happened during the communication process.

Types of HTTP status codes

HTTP status codes are grouped into different classes, each representing a different category of response. Here are the main classes:

1. Informational (1xx): These codes indicate that the request has been received and the server is continuing to process it. They are used to provide interim responses during long-running requests.

2. Success (2xx): These codes indicate that the request was successfully received, understood, and accepted by the server. They signify a successful communication between the client and server.

3. Redirection (3xx): These codes indicate that further action needs to be taken by the client to fulfill the request. They are used when a resource has been moved or temporarily unavailable.

4. Client errors (4xx): These codes indicate that the client has made a mistake or has requested something that cannot be fulfilled. They are usually the result of faulty requests, invalid parameters, or unauthorized access.

5. Server errors (5xx): These codes indicate that an error occurred while the server was fulfilling a valid request. They are typically caused by faults on the server-side or temporary server overload.

Common HTTP status codes

Here are some commonly encountered HTTP status codes:

– 200 OK: The request was successful, and the server has returned the requested resource.
– 404 Not Found: The requested resource could not be found on the server.
– 500 Internal Server Error: The server encountered an unexpected condition that prevented it from fulfilling the request.

It is important to note that HTTP status codes are not limited to these examples and there are many more codes with specific meanings. The full list of HTTP status codes along with their descriptions can be found in the HTTP/1.1 specification.


HTTP status codes play a crucial role in web communication, providing information about the status and outcome of client-server requests. By understanding and interpreting these codes, both clients and servers can ensure effective communication and troubleshoot issues more efficiently. So the next time you encounter a “404 Not Found” or “500 Internal Server Error” message, you’ll have a better understanding of what it means. Keep in mind that a successful communication starts with the appropriate HTTP status code.

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