Parsing the status codes of the HTTP protocol: common status codes and their meanings

HTTP (Hypertext Transfer Protocol) protocol is the basis of Internet communication. It defines the rules for communication between the client and the server. In the HTTP protocol, the status code serves to indicate the status of the client's request. This article will introduce in detail common HTTP status codes and their corresponding meanings.

1xx Informational Responses
1xx status code indicates that the request has been received and the server is still processing it. Under normal circumstances, clients do not need to care too much about these status codes because they will not have a direct impact on the request results.

100 Continue - The request has been received by the server and the client should continue sending the remainder of the request.
101 Switching Protocols - The server will switch protocols based on the client's request.

2xx Successful Responses
2xx status code indicates that the request has been successfully received, understood and processed by the server.

200 OK - Request successful. Generally used for GET and POST requests, indicating that the server successfully returned the resource requested by the client.
201 Created - The request was successfully received by the server and a new resource was created.
204 No Content - The server received the request but returned no content.

3xx Redirection Responses
3xx status code indicates that further operations are required to complete the request.

301 Moved Permanently - The requested resource has been permanently moved to a new location.
302 Found - The requested resource was temporarily moved to a new location. Note that the original URI address should continue to be used.
304 Not Modified - The resource requested by the client has not changed on the server and can be cached.

4xx Client Error Responses
4xx status code indicates that the request sent by the client has an error or cannot be processed by the server.

400 Bad Request - The server cannot parse the client request.
401 Unauthorized - The request requires user authentication.
404 Not Found - The requested resource does not exist.

5xx Server Error Responses
5xx status code indicates that an error occurred when the server processed the request.

500 Internal Server Error - The server encountered an unpredictable error.
502 Bad Gateway - The server acting as a gateway or proxy server received an invalid response from the upstream server.
503 Service Unavailable - The server is temporarily unable to handle requests and is down due to temporary overload or maintenance.

In addition to the common status codes listed above, the HTTP protocol also has some other status codes, each of which has a specific meaning. After receiving different status codes, the client can handle them accordingly.

It should be noted that although the HTTP protocol defines a large number of status codes, there are relatively few status codes commonly used in actual applications. During development, we should become familiar with these common status codes to better understand the server's response to requests.

In summary, the HTTP protocol status code is a way of transmitting information between the client and the server. It is very important for developers to understand common status codes and their corresponding meanings. Only by correctly understanding status codes and handling them accordingly can we better control the network communication process and improve user experience.

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