10 Most Common HTTP Status Codes

When you visit a website or make a request online, your browser communicates with a server using HTTP (Hypertext Transfer Protocol). The server responds with a three-digit HTTP status code that indicates whether the request was successful or if something went wrong. These codes are grouped into categories and help explain the outcome of your request in a simple way.

This guide explains the major HTTP status code categories and highlights some of the most common codes with their meanings, making it easy to understand what happens when you interact with a website.

What are HTTP Status Codes?

The HTTP status code is a response made by the server to the client's request. These are three-digit codes. There are over 60 status codes, but they fall into five main categories:

• 1xx - Informational Response (These status codes are all about the information received by the server when a request is made).
• 2xx - Success (This status code depicts that the request made has been fulfilled by the server and the expected response has been achieved).
• 3xx - Redirection (The requested URL is redirected elsewhere).
• 4xx - Client Errors (This indicates that the page is not found).
• 5xx - Server Errors (A request made by the client but the server fails to complete the request). 

Major HTTP Status Codes

1. 200  (Success/OK)

The HTTP status code 200 represents success which means the page you have requested has been fetched. The action made has been accepted and has been delivered to the client by delivering the requested page. 

• GET: entity in reference to the requested source sent to the response
• POST: entity describing the response of action made
• HEAD: an entity-header field similar to the requested source 
• TRACE: a request made by the client is taken care of by the server

2. 301 (Permanent Redirect)

The HTTP status code 301 means that the page you have requested has moved to a new URL and which is permanent. In the future, whenever the user requests the same website, it will be redirected to the new URL. The modified permanent URL is given by the location filed in response. 

3. 302 (Temporary Redirect)

The requested URL has been redirected to another website which is temporary. Major changes in the URL will be in the future. Other than GET or HEAD, if the 302 is received in response to a request. The redirection is temporarily redirected to another website. 

4. 304 (Not Modified)

HTTP status code 304 is used for caching purposes. The response has not been changed so that in the future the client can resume the same cache. If there's a GET request and access is allowed, but the document has not been modified. The response MUST NOT contain a message-body and therefore comes to an end by the first empty line. 

5. 400 (Bad Request)

When the client requests a page and the server is not able to understand anything, it displays a 400 HTTP status code. The client SHOULD NOT repeat the request without any changes. The request can be a malformed, deceptive request routing, or invalid request.

6. 401 (Unauthorized Error)

This HTTP status code requires user authentication. The response includes the WWW-Authenticate header field containing a challenge applied to a requested source. HTTP access authentication "HTTP Authentication: Basic and Digest Access Authentication".

7. 403 (Forbidden)

The HTTP status code 403 implies that the request is understood by the server, but still refuses to fulfill it. If the request method was not HEAD and also the server wants to make it public when the request is not completed, it SHOULD tell the reason for the refusal in the entity. 

8. 404 (Not Found)

404 HTTP Status code appears when you request a URL and then the server has not found anything. This happens when the server doesn't wish to describe the reason why the request has been refused. Also, the server is not able to find a representation for the target resource. 

9. 500 (Internal Server Error)

500 HTTP status code means requesting a URL is not fulfilled because the server encounters an unexpected condition. It gives information about the request made if it is successful, and throws an error. When there's an error during a connection to the server, and the requested page cannot be accessed then this message is displayed. 

10. 501 (Not Implemented)

When a request is made by the client, the server is not able to recognize the request method and is not able to support any resource. By default. it is cacheable. The methods, the server requires to support are GET and HEAD. The server does not support the functionality required to fulfill the request. 

Other HTTP Status Codes Are:

100 Continue 

101 Switching Protocol 

102 Processing (WebDAV) 

103 Early Hints 

200 OK 

201 Created 

202 Accepted 

203 Non-Authoritative Information 

204 No Content 

205 Reset Content 

206 Partial Content 

207 Multi-Status (WebDAV) 

208 Already Reported (WebDAV)

226 IM Used (HTTP Delta encoding) 

300 Multiple Choice

301 Moved Permanently 

302 Found

303 See Other

304 Not Modified 

305 Use Proxy 

306 Unused 

307 Temporary Redirect 

308 Permanent Redirect 

400 Bad Request 

401 Unauthorized 

402 Payment Required 

403 Forbidden 

404 Not Found 

405 Method Not Allowed

406 Not Acceptable 

407 Proxy Authentication Required

408 Request Timeout

409 Conflict 

410 Gone

411 Length Required 

412 Precondition Failed 

413 Payload Too Large 

414 URI Too Long 

415 Unsupported Media Type 

416 Range Not Satisfiable 

417 Expectation Failed 

418 I'm a teapot

421 Misdirected Request

425 Too Early 

426 Upgrade Required 

428 Precondition Required

429 Too Many Requests 

431 Request Header Fields Too Large

451 Unavailable For Legal Reasons 

500 Internal Server Error 

501 Not Implemented 

502 Bad Gateway

503 Service Unavailable 

504 Gateway Timeout 

505 HTTP Version Not Supported 

506 Variant Also Negotiates 

507 Insufficient Storage (WebDAV)

508 Loop Detected (WebDAV) 

510 Not Extended 

511 Network Authentication Required

Why HTTP Status Codes Matter

Understanding HTTP status codes helps you figure out what’s happening when you interact with a website. Whether it’s a successful page load (200), a missing page (404), or a server issue (500), these codes provide clarity about the communication between your browser and the server. They’re especially useful for developers and website administrators to troubleshoot issues and improve user experiences.

Conclusion

HTTP status codes are like the internet’s way of talking to you about what’s happening behind the scenes. From confirming a successful request (2xx) to pointing out a missing page (404) or a server hiccup (500), these codes make it easier to understand and fix issues when browsing the web. By familiarizing yourself with these codes, you can better navigate errors, optimize websites, or simply know why a page didn’t load as expected. Whether you’re a casual user or a developer, knowing the basics of HTTP status codes empowers you to interact with the digital world more confidently.