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    Event

    A message on the event bus that something happened, like a state change or a button press. Any code can listen to events.

    In code
    hass.busEVENT_STATE_CHANGEDEventEntity
    Also
    events, event bus

    Home Assistant fires events for many things: a state change, an action being performed, Home Assistant starting. Automations can trigger on them.

    Not to be confused with event entities: entities of the event type, which show the last thing that happened on a device, like a button press.

    Related terms

    • State machineThe part of Home Assistant Core that holds the current state of every entity.
    • TriggerWhat starts an automation, like a state change, a time, or an event.
    • The hass objectThe `HomeAssistant` instance that integrations get, with access to the state machine, the event bus, actions, and the configuration.