This type of status code means that the request has been accepted and needs to be processed. This type of response is a provisional response, containing only a status line and some optional response header information, and ends with a blank line. Since no 1xx status code is defined in the HTTP/1.0 protocol, the server is prohibited from sending 1xx responses to such clients except under certain experimental conditions.

This type of status code means that the request has been successfully received, understood, and accepted by the server.
3xx redirect
These status codes indicate that further action by the client is required to complete the request. Usually, these status codes are used for redirection, and the subsequent request address (redirection target) is specified in the Location field of this response.

indicate that what appears to be an error on the client side is preventing the server from processing. Unless the response is a HEAD request, the server should return an entity explaining the current error condition, and whether this is a temporary or permanent condition. These status codes apply to any request method. The browser SHOULD display to the user any physical content contained in such error responses.

indicates that the server was unable to fulfill an obviously valid request. This type of status code means that the server has an error or an abnormal state in the process of processing the request, or it may be that the server realizes that the processing of the request cannot be completed with the current software and hardware resources. Unless this is a HEAD request, the server SHOULD include an EXPLAIN_INFO entity explaining the current error state and whether the condition is temporary or permanent. The browser SHOULD display to the user any entities contained in the current response. These status codes apply to any response method.

Please check the Wiki for details
https://zh.wikipedia.org/zh-tw/HTTP status code