The capacity of an application to display visual elements on top of other running applications is a system-level permission. This allows a program to create floating windows, display persistent notifications, or overlay information directly onto the screen regardless of which application is currently in the foreground. For example, a messaging app might use this permission to show a chat bubble that remains visible even when the user switches to a different application.
The functionality enables enhanced user experiences by providing constant accessibility to essential features or information. Historically, this capability was limited and required more advanced system-level modifications. However, modern operating systems provide structured APIs for developers to implement this feature in a controlled and secure manner. This enhances multitasking efficiency and allows for more seamless interactions, presenting information or controls without requiring users to constantly switch between applications.