What is the invisible app?

Excuse me, could you please elaborate on what exactly the "invisible app" is? Is it a new type of software that operates without a visible user interface? Or is it perhaps a stealth application designed to remain undetected by the user or others? I'm curious to know if it has any specific use cases or functions that make it unique from other apps on the market. Additionally, I'm wondering if there are any potential security risks associated with using such an app, and if so, how can users mitigate those risks? Thank you for your time and clarification.