HTTP Status Codes

HTTP status codes are three-digit numbers returned by a server in response to a client's request. They indicate whether the request was successful, redirected, or resulted in an error. Every HTTP response includes exactly one status code.

Status Code Categories

• 1xx Informational: The request was received and the server is continuing to process it. These are provisional responses. Example: 100 Continue — The server has received the request headers, and the client should proceed to send the request body.
• 2xx Success: The request was received, understood, and accepted successfully. Example: 200 OK — The standard response for successful HTTP requests. The actual response will depend on the request method used.
• 3xx Redirection: Further action is needed to complete the request, typically a redirect to a different URL. Example: 301 Moved Permanently — This and all future requests should be directed to the given URI.
• 4xx Client Error: The request contains bad syntax or cannot be fulfilled. The error is on the client side. Example: 404 Not Found — The requested resource was not found on the server.
• 5xx Server Error: The server failed to fulfill a valid request. The error is on the server side. Example: 500 Internal Server Error — A generic error message when the server encounters an unexpected condition.

Common Use Cases

• API Development: Choose the correct status code for REST API responses
• Debugging: Understand error responses from servers and APIs
• SEO: Ensure proper redirect codes (301 vs 302) for search engine optimization
• Monitoring: Interpret status codes in server logs and monitoring dashboards

HTTP status codes are a fundamental part of web communications, providing quick insights into the transactional status of HTTP requests and responses, guiding subsequent actions by clients, and aiding in the proper functioning of web services and APIs.