A destination (a connection in the schema) is a pipe that receives every event a product synthesises. A product can have many; each delivers independently.
Supported destinations are Accoil, Segment, PostHog, Amplitude, Mixpanel, and any plain REST endpoint. Each carries a write key (a secret, stored encrypted and never shown back) and a small configuration (non-secret values like a base URL or region).
One config choice is set once and never changed: the group identifier — whether events group customers by entitlement_number or entitlement_id. Switching it later would re-key every group in the destination and fragment that pipe's analytics history, so the destination is effectively immutable: to change it you remove the connection and add a new one.
A destination can be enabled or disabled, and its full history can be replayed down the pipe on demand.