English: The high-level design of onion services. The client and onion service each select three relays (a guard and two middle relays) to route traffic to each other, never leaving the Tor network, and never transmitting plaintext. Note that this diagram is simplified; e.g., the client's second middle relay is actually the rendezvous relay during the handshake, so is known to both the client and the server (but is still used as the client's second middle relay as shown).