# API Entrance Trigger for Sequences

Use the API Entrance trigger for entering and exiting audiences from your own systems. Enroll the same user in a Sequence multiple times, or launch several Sequences from one event.

The API Entrance trigger initiates a Sequence for the audience members specified in a call to a Journeys API endpoint. Each call can include an `entrance_id` to tag the enrollment, so the same user can be enrolled in the same Sequence multiple times without overwriting earlier enrollments.

The trigger supports the following capabilities:

* **Concurrent enrollments per user** — Tag each entry with a unique `entrance_id` so the same user can be enrolled in multiple instances of a Sequence at the same time. A passenger booked on two flights six hours apart gets independent enrollment in each, with no overwrites.
* **Multi-Sequence fan-out** — Configure the same `triggering_id` on more than one Sequence so a single API call enters audiences into all of them. One customer order can start several post-purchase campaigns at once.
* **Targeted exits** — Cancel all in-flight users for a specific `entrance_id` in one call. If a store event is cancelled, exit everyone enrolled for that event without needing to identify them individually.

## Documentation

For full details, see the [API Entrance trigger](https://www.airship.com/docs/guides/messaging/messages/sequences/triggers/#api-entrance) and the [Journeys API reference](https://www.airship.com/docs/developer/rest-api/ua/operations/journeys/).