Tell me about HTTP status codes.

HTTP status codes are three-digit integers returned by the server in response to a client's request. They indicate the result of the request and are divided into five classes:

• 1xx Informational: Request received, processing continues.
  • 100 Continue: The initial part of the request has been received, and the client can continue sending the rest.
  • 101 Switching Protocols: The server understands and is willing to comply with the request to switch protocols.
• 2xx Success: The request was successfully received, understood, and accepted.
  • 200 OK: Standard response for successful HTTP requests.
  • 201 Created: The request has been fulfilled and resulted in a new resource being created.
  • 204 No Content: The server successfully processed the request, but no content is returned.
• 3xx Redirection: Further action is needed to complete the request.
  • 301 Moved Permanently: The resource has a new permanent URI.
  • 302 Found: The resource is temporarily under a different URI.
  • 304 Not Modified: The resource has not changed since the last request.
• 4xx Client Error: The request contains bad syntax or cannot be fulfilled.
  • 400 Bad Request: The server could not understand the request due to invalid syntax.
  • 401 Unauthorized: Authentication is required.
  • 403 Forbidden: The server understood the request, but refuses to authorize it.
  • 404 Not Found: The requested resource was not found.
• 5xx Server Error: The server failed to fulfill an apparently valid request.
  • 500 Internal Server Error: A generic error message.
  • 502 Bad Gateway: The server, while acting as a gateway, received an invalid response.
  • 503 Service Unavailable: The server is not ready to handle the request.

Examples in testing:

• API testing: Check if the returned status codes match expectations (e.g., 200 OK for success, 404 Not Found for missing resource).
• Web application testing: Check redirects (3xx), user input errors (4xx), service availability (503).

Example in Python with requests:

import requests

url = "https://www.example.com"
response = requests.get(url)

# Check if request was successful (status code 2xx)
if response.status_code == 200:
    print("Request successful.")
else:
    print(f"Error: Status code {response.status_code}")