Adobe Analytics - Unique Visitor

Hi,

I am Bala, I am am working on the digital space for 6 months. I have a query regarding the Adobe Analytics metrics - Unique Visitor.

I have the unique visitor definition from adobe

https://marketing.adobe.com/resources/help/en_US/reference/reports_unique_visitors_v15_dsc.html

But, I would like to know how it captures it, Is there any Unique ID which is used to capture the Unique Visitor o what is the internal logic behind to capture Unique Visitor. We certainly need this clarification as to confirm our numbers.

Ex : We are into Mobile Application, We need to know how many customers has launched the app in their device !. So Does Adobe calculates the Unique Visitor based or any device id /Unique Id or any other internal logic.

It would be great if you could reply asap.

Thanks,

Bala