What is a hidden service?
Servers configured to receive inbound connections only through Tor are called hidden services. Rather than utilizing a server's IP address (and thus its network location,) a hidden service is accessed through its . onion address.
What is hidden service protocol?
Hidden Service Protocol. The hidden service creates a Service Descriptor containing it's Public key for Authentication and the IP Addresses of the Relays acting as introduction points. The Service Descriptor gets signed with the hosts private key.