Which OutSystems component is used to define user interfaces for mobile applications?

The component used to define user interfaces for mobile applications in OutSystems is the Screen. Screens serve as the primary building blocks for user-facing parts of the application, allowing developers to create a visual representation of the application’s flow and functionality.

Each Screen can contain various interface elements such as buttons, text fields, and images, which are essential for user interactions. This enables developers to design how users will navigate through the application, input information, and engage with the provided features.

In contrast, other options like Module, Entity, and Action serve different purposes. A Module is a larger structural unit that can contain multiple Screens, Actions, and Entities, while an Entity pertains to data storage, representing data models within the application. An Action is a piece of logic that can be executed, typically to manipulate data or control application behavior, but does not itself define any user interface elements. Thus, the role of the Screen is specifically focused on the user interface, making it the correct answer for this question.