Which component is essential for a Flow but not for a Subflow?

The essential component for a Flow, but not for a Subflow, is the Trigger. In ServiceNow Flow Designer, a Flow is initiated by a specific event or condition known as a Trigger. This could be an update on a record, the creation of a new record, or a scheduled time when certain conditions are met. The Trigger serves as the starting point for the Flow, determining when it will execute automatically in response to changes in the system or user inputs.

Subflows, on the other hand, are designed to be reusable processes that can be called from within other Flows or even from other Subflows. They are meant to encapsulate logic that is called upon by different Flows, and as such, they do not have their own Trigger. Instead, Subflows rely on the context and the inputs provided by the Flow that invokes them.

Understanding this distinction is crucial for effectively organizing and implementing automation in ServiceNow, as the Trigger in a Flow allows it to respond dynamically to changes, while Subflows facilitate modular and reusable components within that broader automation framework.