HTTP (Hypertext Transfer Protocol)

HTTP (Hypertext Transfer Protocol) is the set of rules for transferring files (text, graphic images, sound, video, and other multimedia files) on the World Wide Web.
When a user opens their Web browser, the user is indirectly making use of HTTP.
HTTP is an application protocol that runs on top of the TCP/IP protocols.

HTTP Status Codes

HTTP_STATUS_CONTINUE

100

The request can be continued.

HTTP_STATUS_SWITCH_PROTOCOLS

101

The server has switched protocols in an upgrade header.

HTTP_STATUS_OK

200

The request completed successfully.

HTTP_STATUS_CREATED

201

The request has been fulfilled and resulted in the creation of a new resource.

HTTP_STATUS_ACCEPTED

202

The request has been accepted for processing, but the processing has not been completed.

HTTP_STATUS_PARTIAL

203

The returned meta information in the entity-header is not the definitive set available from the origin server.

HTTP_STATUS_NO_CONTENT

204

The server has fulfilled the request, but there is no new information to send back.

HTTP_STATUS_RESET_CONTENT

205

The request has been completed, and the client program should reset the document view that caused the request to be sent to allow the user to easily initiate another input action.

HTTP_STATUS_PARTIAL_CONTENT

206

The server has fulfilled the partial GET request for the resource.

HTTP_STATUS_AMBIGUOUS

300

The server couldn't decide what to return.

HTTP_STATUS_MOVED

301

The requested resource has been assigned to a new permanent URI (Uniform Resource Identifier), and any future references to this resource should be done using one of the returned URIs.

HTTP_STATUS_REDIRECT

302

The requested resource resides temporarily under a different URI (Uniform Resource Identifier).

HTTP_STATUS_REDIRECT_METHOD

303

The response to the request can be found under a different URI (Uniform Resource Identifier) and should be retrieved using a GET HTTP verb on that resource.

HTTP_STATUS_NOT_MODIFIED

304

The requested resource has not been modified.

HTTP_STATUS_USE_PROXY

305

The requested resource must be accessed through the proxy given by the location field.

HTTP_STATUS_REDIRECT_KEEP_VERB

307

The redirected request keeps the same HTTP verb. HTTP/1.1 behavior.

HTTP_STATUS_BAD_REQUEST

400

The request could not be processed by the server due to invalid syntax.

HTTP_STATUS_DENIED

401

The requested resource requires user authentication.

HTTP_STATUS_PAYMENT_REQ

402

Not currently implemented in the HTTP protocol.

HTTP_STATUS_FORBIDDEN

403

The server understood the request, but is refusing to fulfill it.

HTTP_STATUS_NOT_FOUND

404

The server has not found anything matching the requested URI (Uniform Resource Identifier).

HTTP_STATUS_BAD_METHOD

405

The HTTP verb used is not allowed.

HTTP_STATUS_NONE_ACCEPTABLE

406

No responses acceptable to the client were found.

HTTP_STATUS_PROXY_AUTH_REQ

407

Proxy authentication required.

HTTP_STATUS_REQUEST_TIMEOUT

408

The server timed out waiting for the request.

HTTP_STATUS_CONFLICT

409

The request could not be completed due to a conflict with the current state of the resource. The user should resubmit with more information.

HTTP_STATUS_GONE

410

The requested resource is no longer available at the server, and no forwarding address is known.

HTTP_STATUS_LENGTH_REQUIRED

411

The server refuses to accept the request without a defined content length.

HTTP_STATUS_PRECOND_FAILED

412

The precondition given in one or more of the request header fields evaluated to false when it was tested on the server.

HTTP_STATUS_REQUEST_TOO_LARGE

413

The server is refusing to process a request because the request entity is larger than the server is willing or able to process.

HTTP_STATUS_URI_TOO_LONG

414

The server is refusing to service the request because the request URI (Uniform Resource Identifier) is longer than the server is willing to interpret.

HTTP_STATUS_UNSUPPORTED_MEDIA

415

The server is refusing to service the request because the entity of the request is in a format not supported by the requested resource for the requested method.

HTTP_STATUS_RETRY_WITH

449

The request should be retried after doing the appropriate action.

HTTP_STATUS_SERVER_ERROR

500

The server encountered an unexpected condition that prevented it from fulfilling the request.

HTTP_STATUS_NOT_SUPPORTED

501

The server does not support the functionality required to fulfill the request.

HTTP_STATUS_BAD_GATEWAY

502

The server, while acting as a gateway or proxy, received an invalid response from the upstream server it accessed in attempting to fulfill the request.

HTTP_STATUS_SERVICE_UNAVAIL

503

The service is temporarily overloaded.

HTTP_STATUS_GATEWAY_TIMEOUT

504

The request was timed out waiting for a gateway.

HTTP_STATUS_VERSION_NOT_SUP

505

The server does not support, or refuses to support, the HTTP protocol version that was used in the request message.