How and when is a finger sweep performed?

You're asking about a "finger sweep" in a context that needs more information. There are many possible interpretations, as "finger sweep" can refer to a variety of actions.

To understand what you're asking, please provide more context! For example, are you referring to:

* A medical procedure: Is this a medical procedure where a doctor or healthcare professional sweeps their finger across a body part?

* A musical technique: Are you asking about a technique used by musicians to play a musical instrument?

* A computer interaction: Are you asking about a specific computer action using a finger on a touch screen?

* Something else entirely?

Once I understand the context, I can provide you with a helpful and accurate answer.