# Glossary

## Terms and Definitions

| Term                     | Definition                                                                                                                                                                                                                                                                                                                                                                                        |
| ------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Guardian                 | One of 19 validators in Wormhole's Guardian Network.                                                                                                                                                                                                                                                                                                                                              |
| Guardian Network         | <p>Wormhole's decentralized oracle network, consisting of 19 validators (Guardians).</p><p></p><p>The current list of Guardians can be viewed <a href="https://wormhole.com/network/">here</a>.</p>                                                                                                                                                                                               |
| Guardian Spy             | <p>A Guardian node that only observes and forwards network traffic to help scale VAA distribution.</p><p></p><p>This service does not validate any VAAs.</p>                                                                                                                                                                                                                                      |
| LayerZero Endpoint       | <p>The smart contract by which all LayerZero messages are emitted and verified.<br><br>LayerZero deploys this contract to every chain they want to support.</p>                                                                                                                                                                                                                                   |
| Message-Passing Protocol | A protocol that facilitates sending arbitrary data from one blockchain to another blockchain (i.e., LayerZero or Wormhole).                                                                                                                                                                                                                                                                       |
| Relayer                  | The off-chain service that processes and delivers cross-chain messages.                                                                                                                                                                                                                                                                                                                           |
| Spy Listener             | The off-chain service that listens to a Guardian Spy node for Ax Protocol-specific VAAs via a gRPC stream.                                                                                                                                                                                                                                                                                        |
| VAA                      | <p><a href="https://book.wormhole.com/wormhole/4_vaa.html">Verifiable Action Approvals (VAAs)</a> are the core messaging primitive in Wormhole. You can think of them as packets of xData that are emitted any time an xDapp contract interacts with Wormhole's Core Bridge Contract.</p><p></p><p>The VAAs are signed by the Guardians and need 13/19 signatures to be considered authentic.</p> |
| Wormhole Core Bridge     | <p>The smart contract by which all Wormhole messages are emitted and verified.<br><br>Wormhole deploys this contract to every chain they want to support.</p>                                                                                                                                                                                                                                     |