What does 503 Service Unavailable mean?

The "503 Service Unavailable" status code is an HTTP response indicating that the server is temporarily unable to handle the request. This is often due to server overload, maintenance, or temporary issues with the server infrastructure. The server may become available again once the issue is resolved.

For example, if a website undergoes scheduled maintenance or experiences a sudden spike in traffic that exceeds its capacity, it might return a 503 error. This error notifies the users that the server is currently unavailable but may be back online shortly. In some cases, a "Retry-After" header may be included to specify when the server will be available again.