Mastering HTTP Status Codes: A Complete Guide to 1xx–5xx Responses

What are HTTP Status Codes

HTTP status codes are three‑digit numbers returned by a server to indicate the result of a client’s request. They consist of the numeric code and a reason phrase (e.g., 200 OK, 404 Not Found).

Categories

1xx – Informational : Request received and processing continues.

2xx – Success : The request was successfully received, understood, and accepted.

3xx – Redirection : Further action is needed to complete the request.

4xx – Client Error : The request contains bad syntax or cannot be fulfilled.

5xx – Server Error : The server failed to fulfill a valid request.

2xx – Success

200 OK : Standard response for successful HTTP requests.

204 No Content : The server successfully processed the request but returned no body.

206 Partial Content : Used for range requests; the server returns only the specified part of the resource, indicated by the Content-Range header.

3xx – Redirection

301 Moved Permanently : The resource has a new permanent URI.

302 Found : The resource resides temporarily under a different URI.

4xx – Client Errors

400 Bad Request : The request syntax is malformed.

401 Unauthorized : Authentication is required and has failed or not been provided.

403 Forbidden : The server understands the request but refuses to authorize it.

404 Not Found : The requested resource could not be found, often due to an incorrect URL.

5xx – Server Errors

500 Internal Server Error : The server encountered an unexpected condition that prevented it from fulfilling the request.

503 Service Unavailable : The server is currently unable to handle the request due to overload or maintenance.