Final answer:
The overall purpose of an app is to address a specific need for its users, with functionalities that align with that purpose and both input and output that facilitate this utility. The functionality is the array of tasks the app can perform, while the inputs and outputs are the types of data received and presented by the app, respectively.
Step-by-step explanation:
The overall purpose of an app can widely vary, but fundamentally, it is designed to perform specific functions that solve problems or enhance the user's experience in some way. When creating an app, one must consider the target audience and the primary need that the app will address. This includes ensuring that the functionalities align with the purpose of the app, be it entertainment, education, productivity, or any other sector.
Regarding the functionality of an app, it includes all the tasks that the app can perform, such as allowing users to enter data, process it, and provide the desired outcome. For example, a note-taking app's functionality might include creating notes, organizing them into folders, and searching through the content. These functionalities are what differentiate one app from another and are critical in providing a unique value proposition to the end-users.
The inputs for an app could be anything from user-entered text, photos, videos, or sensor data, while outputs might include displaying information on the screen, sounds, notifications, or the transmission of data to other apps or services. Continuing with the note-taking app example, the input could be the user typing notes, and the output would be the display of these notes in an organized fashion, accessible for future reference.