Glossary

Term	Definition
Message	A single SMS with full lifecycle tracking - body, recipient, status, attempt history, cost. The smallest unit in the grouping hierarchy. See Messages.
Attempt	One try at sending a message through AWS. A message can have multiple attempts (retries), each with its own status and cost.
Communication	A logical batch of messages treated as one unit. The deduplication key: the same phone cannot receive two messages with the same `communicationId`. See Communications & Campaigns.
Campaign	A group of one or more communications over time. Purely aggregative - no deduplication semantics of its own.
Phone	A global phone number record (E.164) with validation status, opt-out status, carrier info, and aggregate stats. Shared by all tenants. See Phones & Opt-Out.
Tenant	An organization using Outpost. The top-level ownership unit - all data and stats are scoped under a tenant. See Tenants & Projects.
Project	A configuration container under a tenant: API keys, webhook configs, and compliance settings. Also a stats dimension.
API key	Credential for the REST API, sent in `x-api-key`. Admin keys have full access; tenant keys are scoped to one tenant and project. See API Keys.
Event	An immutable audit log entry tracking a message lifecycle change or phone state change. See Events.
Stat	A pre-aggregated counter (by dimension and time window) powering fast analytics. See Stats.
Webhook	An HTTP callback configured on a project that forwards subscribed events to an external endpoint. See Webhooks.
Settled	A message's terminal state - `DELIVERED`, `FAILED`, or `BLOCKED`. `FAILED` is written exactly once, at the moment a message settles as failed; it never appears as an intermediate, retryable state. Settlement triggers cost recording, stats, and webhooks, and is irreversible.
Auto-materialization	Outpost creating a communication, campaign, or phone record automatically the first time it is referenced, instead of requiring pre-registration.
DLR	Delivery receipt - the carrier network's asynchronous verdict on a send, processed by the DLR worker.
Two-way SMS	Inbound replies from recipients, including STOP/START/HELP keyword handling. See Workers - two-way worker.
Opt-out footer	Compliance text appended to outbound messages - either a "Reply STOP" reminder or an opt-out link. See Messages.
Shared route	An AWS origination identity used when the destination country has no dedicated number in the pool. Shared routes cannot receive replies, so opt-out link footers are mandatory there.
E.164	The international phone number format (`+15551234567`) used as the phone record's natural key.