What does the HTTP status code 403 'That's an error' mean?

The HTTP status code 403, often accompanied by the message 'That's an error', signifies a 'Forbidden' error. It means the server understands the request, but refuses to authorize it. Unlike a 401 error (Unauthorized), a 403 error indicates that authentication won't make a difference; the client is not allowed to access the resource, regardless of credentials. This can be due to permission restrictions, IP address blocking, or other server-side configurations.