Final answer:
The item that occupies a single cell on the Home screen and allows users to launch an app is known as an icon. Icons are designed for easy recognition and use, letting users access apps quickly on smartphones and tablets.
Step-by-step explanation:
The item that typically occupies a single cell on the Home screen of a smartphone or tablet and provides a way for users to start an app is called an icon. Each of these icons represents a different application that can be opened with a tap. When you touch one of these icons, the operating system of the device launches the corresponding app, allowing you to use its features and functions. The arrangement and organization of these icons can usually be customized by the user to suit their preferences, often with the ability to group them into folders or move them to different screens for easier access.
Smartphones and tablets utilize a grid-like pattern on their Home screens to systematically arrange these icons. This user interface design allows for a clean and accessible way to navigate between different apps quickly. Visual simplicity and ease of use are important aspects of app icon design, as they help users recognize and open their desired app without confusion.