What are the 5 categories of HTTP status codes?

HTTP status codes are grouped into 5 categories: 1xx Informational, 2xx Success, 3xx Redirection, 4xx Client Error, and 5xx Server Error. Each category indicates a different class of response from the server.

What is the difference between 401 Unauthorized and 403 Forbidden?

401 Unauthorized means authentication is required and has failed or not been provided. 403 Forbidden means the request was valid but the server is refusing to respond, typically because the authenticated user lacks permission.

Which HTTP status code should I use for a permanent redirect?

Use 301 Moved Permanently for a permanent redirect. If the HTTP method must be preserved (e.g., POST should remain POST), use 308 Permanent Redirect instead.

Reference

HTTP Status Codes Reference

Complete reference of HTTP status codes with descriptions, categories, and usage examples.

Last updated: 2026-08-27

code	name	category	description
100	Continue	1xx Informational	The server has received the request headers and the client should proceed to send the request body.
101	Switching Protocols	1xx Informational	The requester has asked the server to switch protocols and the server has agreed.
200	OK	2xx Success	The request has succeeded.
201	Created	2xx Success	The request has been fulfilled and a new resource has been created.
202	Accepted	2xx Success	The request has been accepted for processing but not complete.
204	No Content	2xx Success	The server successfully processed the request and is not returning any content.
206	Partial Content	2xx Success	The server is delivering only part of the resource due to a range header.
301	Moved Permanently	3xx Redirection	The resource has been permanently moved to a new URL.
302	Found	3xx Redirection	The resource is temporarily under a different URL.
304	Not Modified	3xx Redirection	The resource has not been modified since the last request.
307	Temporary Redirect	3xx Redirection	The resource is temporarily under a different URL, same method must be used.
308	Permanent Redirect	3xx Redirection	The resource has permanently moved, same method must be used.
400	Bad Request	4xx Client Error	The server cannot process the request due to a client error.
401	Unauthorized	4xx Client Error	Authentication is required and has failed or not been provided.
403	Forbidden	4xx Client Error	The request was valid but the server is refusing action.
404	Not Found	4xx Client Error	The requested resource could not be found.
405	Method Not Allowed	4xx Client Error	The request method is not supported for this resource.
408	Request Timeout	4xx Client Error	The server timed out waiting for the request.
409	Conflict	4xx Client Error	The request could not be processed because of conflict.
410	Gone	4xx Client Error	The resource is no longer available and will not be available again.
418	I'm a Teapot	4xx Client Error	The server refuses to brew coffee because it is a teapot.
429	Too Many Requests	4xx Client Error	The user has sent too many requests in a given amount of time.
500	Internal Server Error	5xx Server Error	A generic error message for unexpected server errors.
501	Not Implemented	5xx Server Error	The server does not support the functionality required.
502	Bad Gateway	5xx Server Error	The server received an invalid response from an upstream server.
503	Service Unavailable	5xx Server Error	The server is currently unavailable due to maintenance or overload.
504	Gateway Timeout	5xx Server Error	The server did not receive a timely response from the upstream server.
511	Network Authentication Required	5xx Server Error	The client needs to authenticate to gain network access.

Frequently Asked Questions

What are the 5 categories of HTTP status codes?: HTTP status codes are grouped into 5 categories: 1xx Informational, 2xx Success, 3xx Redirection, 4xx Client Error, and 5xx Server Error. Each category indicates a different class of response from the server.
What is the difference between 401 Unauthorized and 403 Forbidden?: 401 Unauthorized means authentication is required and has failed or not been provided. 403 Forbidden means the request was valid but the server is refusing to respond, typically because the authenticated user lacks permission.
Which HTTP status code should I use for a permanent redirect?: Use 301 Moved Permanently for a permanent redirect. If the HTTP method must be preserved (e.g., POST should remain POST), use 308 Permanent Redirect instead.