HTTP status code is a set of three digits used to indicate the server's response to the request after the client initiates a request to the server. The following are common HTTP status codes and their meanings:
1xx (informational status code): Indicates that the request has been received and processing continues.
- 100 Continue: The server normally receives part of the request sent by the client, indicating that it can continue to send the remaining requests.
2xx (success status code): Indicates that the request has been successfully received, understood, and processed.
200 OK: The server successfully processed the request sent by the client.
201 Created: The server successfully created a new resource.
204 No Content: The server successfully processed the client's request but did not return any content.
3xx (redirect status code): Indicates that the request requires further operations to complete the request.
301 Moved Permanently: The requested page has been permanently moved to a new location.
302 Found: The requested page has been temporarily moved to a new location.
304 Not Modified: The requested resource has not been modified and the cached version can be used directly.
4xx (client error status code): Indicates that there is a problem with the client's request.
400 Bad Request: The server cannot understand the request sent by the client.
401 Unauthorized: The request was not authenticated or failed.
403 Forbidden: Access to the requested resource is denied.
404 Not Found: The requested page does not exist.
5xx (server error status code): Indicates that an error occurred when the server processed the request.
500 Internal Server Error: The server encountered an error while executing the request.
502 Bad Gateway: The server, acting as a gateway or proxy, received an invalid response from the upstream server.
503 Service Unavailable: The server is currently unable to process the request. This is generally used for server maintenance or overload.
These HTTP status codes can help developers better understand and handle requests initiated by clients to the server, and lock and troubleshoot problems in a timely manner.