402 Payment Required is an HTTP response status code that the source article lists among standard and notable codes. Standardized codes are defined by the IETF in RFC publications and maintained by the IANA, while other values are used by various servers. HTTP status codes indicate the outcome of a client's request to a web server, and their reason phrases are often different in practice or omitted altogether. The code belongs to the group of client error responses.
Background
HTTP status codes are grouped by their first digit into informational, success, redirection, and error classes. The article describes how the 1xx informational responses signal that a request is still being processed, while the 2xx and 3xx groups report success and the need for further client action. The 402 code is presented within this broader system of standardized response values, which are documented through the IETF and kept by the IANA.
Usage and significance
Like other status codes, the 402 response forms part of a common vocabulary that lets clients and servers communicate the state of a request. The article notes that other non-standard values exist in addition to the standardized ones. Understanding these codes helps developers and users interpret how a server has handled a request and what, if anything, should happen next.