HTTP tutorial - Status codes

An overview of the available statuses can be found on the corresponding page of the Mozilla Developer Network MDN.

When using the HTTP protocol, an initiating action of a client is responded to by a response from the server. This action is called synchronous.

Information about the success of the action is provided by a three-digit status code, whereby the first digit indicates the status category.

Status	Function	Description	Examples
1xx	Informal feedback.	Additional information can be transferred to a client here.	101 Continue: This tells the client to proceed with the transmission.
2xx	Successful request.	The request to the HTTP server was successful.	200 Ok: Feedback if request successful. 201 Created: Feedback for the method PUT.
3xx	Diversion information.	A resource is not (no longer) available on the server under the specified URL. The server can signal further information to the client.	301 Moved Permanently: The resource can be reached under a different address. This can then be communicated, for example, in a location header. 304 Not Modified: The available data has not changed since the last request.
4xx	Request error of the client.	The error is located at the calling client, e.g. the login data is missing. A faulty structure in POST/PUT can also be signalled with this.	400 Bad Request: Wrong structure in the body. 401 Authentication failed: Missing or incorrect credentials. 404 Not found: The requested page/resource is not available.
5xx	Server error.	The error is on the server side, e.g. due to an incorrect structure in the request.	500 Server error