Canonical definitions for terms used throughout BaileysEx documentation.
App State Sync (Syncd)
WhatsApp's cross-device settings sync system. It keeps state such as archived chats, mute and pin settings, labels, contact updates, and similar metadata consistent across your linked devices.
Auth State
The collection of cryptographic keys and identity data that represents your connection to WhatsApp. Persisted between sessions so you do not need to re-pair.
Binary Node
WhatsApp's wire format for communication. A compact binary encoding of XML-like structures with a tag, attributes, and content.
Connection
An active, authenticated session with WhatsApp servers. Managed by BaileysEx's supervision tree. One connection maps to one WhatsApp account.
Device
A single client such as a phone, desktop app, or web session linked to a WhatsApp account. WhatsApp's multi-device protocol gives each device its own encryption session.
Double Ratchet
The Signal protocol algorithm that generates unique encryption keys for every message. This gives you forward secrecy, which means older messages stay protected even if newer keys are later exposed.
Event
A notification emitted by a connection when something happens, such as a received message, a presence change, or a group update. You subscribe to events to react to WhatsApp activity in your application.
Community
A WhatsApp container that can organize one or more related groups. BaileysEx exposes
community creation and metadata from the top-level facade and the fuller management
surface through BaileysEx.Feature.Community.
JID
Jabber ID. The address format WhatsApp uses for users, groups, and broadcasts.
Examples: 5511999887766@s.whatsapp.net for a user and 120363001234567890@g.us
for a group.
LID
Logical ID. An alternative addressing mode WhatsApp uses internally for multi-device routing. The protocol maps LIDs to phone-number-based identities when needed.
LTHash
The integrity check WhatsApp uses for app state sync. Instead of trusting every patch blindly, BaileysEx recomputes this rolling hash so it can detect drift or tampering before applying Syncd updates.
Noise Protocol
The transport encryption layer. It establishes an encrypted tunnel over WebSocket before any application data is exchanged.
Newsletter
WhatsApp's channel-style broadcast surface. In BaileysEx, newsletter operations cover metadata lookups, follow and unfollow flows, reactions, and administration helpers.
Pairing
The process of linking BaileysEx to your WhatsApp account. You do this once with a QR code or phone-number verification code, then reuse the saved auth state.
Pre-Key
A one-time-use public key uploaded to WhatsApp servers. It lets other devices start an encrypted session with you even when you are offline.
Sender Key
A shared secret used for group message encryption. It lets one encrypted send cover the whole group instead of encrypting separately for every device.
WAM
WhatsApp Analytics and Metrics. This is WhatsApp's internal event buffer format for client telemetry. BaileysEx can encode and send WAM buffers when you need Baileys parity for that path.
Signal Protocol
The end-to-end encryption protocol used by WhatsApp. Each message is encrypted individually for the recipient device, and BaileysEx handles that workflow for you.
X3DH
Extended Triple Diffie-Hellman. The Signal protocol's key agreement mechanism for establishing a shared secret between two devices that may never have talked before.
XEdDSA
A signature scheme that lets Curve25519 keys also produce Ed25519-compatible signatures. WhatsApp uses this because its identity keys must both exchange keys and sign pre-keys.