Editing HTTP Protocols (section)

== Status Codes ==

HTTP status codes are three-digit numbers returned by the server to indicate the result of a request. They are grouped into five categories based on their first digit.

{| class="wikitable"
! Code Range !! Category !! Description
|-
| 100–199 || Informational Responses || Initial part of the request received; client should continue. Rarely used today.
|-
| 200–299 || Successful Responses || Request was successfully received, understood, and accepted.
|-
| 300–399 || Redirection Messages || Further action is needed by the client, often a new URI.
|-
| 400–499 || Client Error Responses || The request is malformed or cannot be processed due to client-side issues.
|-
| 500–599 || Server Error Responses || Server failed to fulfill a valid request due to internal error or overload.
|}

{| class="wikitable"
! Code !! Category !! Meaning !! Example Scenario
|-
| 100 || Informational || Continue || Client should continue the request
|-
| 101 || Informational || Switching Protocols || Protocol upgrade requested
|-
| 200 || Success || OK || Standard response for successful request
|-
| 201 || Success || Created || Resource successfully created (e.g., via POST)
|-
| 204 || Success || No Content || Request succeeded, no body returned
|-
| 301 || Redirection || Moved Permanently || Resource has a new permanent URI
|-
| 302 || Redirection || Found || Temporarily redirected to another URI
|-
| 304 || Redirection || Not Modified || Cached content is still valid
|-
| 400 || Client Error || Bad Request || Malformed syntax or invalid parameters
|-
| 401 || Client Error || Unauthorized || Authentication required
|-
| 403 || Client Error || Forbidden || Request denied despite authentication
|-
| 404 || Client Error || Not Found || Resource not found at requested URI
|-
| 405 || Client Error || Method Not Allowed || Method not supported on resource
|-
| 408 || Client Error || Request Timeout || Server timed out waiting for request
|-
| 429 || Client Error || Too Many Requests || Rate-limiting or abuse prevention
|-
| 500 || Server Error || Internal Server Error || Generic server failure
|-
| 502 || Server Error || Bad Gateway || Invalid response from upstream server
|-
| 503 || Server Error || Service Unavailable || Server temporarily overloaded or down
|-
| 504 || Server Error || Gateway Timeout || Upstream server did not respond in time
|}