Chapter 7: Interfaces

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The main goals of the chapter are to accomplish the following:

  • Provide an overview of the many different kinds of interfaces.
  • Highlight the main design and research considerations for each of the interfaces.
  • Discuss what is meant by a natural user interface (NUI).
  • Consider which interface is best for a given application or activity.


When considering how to solve a user problem, the default solution that many developers choose to design is an app that can run on a smartphone. Making this easier still are many easy-to-use app developer tools that can be freely downloaded. It is hardly surprising, therefore, to see just how many apps there are in the world. In December 2018, Apple, for example, had a staggering 2 million apps in its store, many of which were games.

Despite the ubiquity of the smartphone app industry, the web continues to proliferate in offering services, content, resources, and information. A central concern is how to design them to be interoperable across different devices and browsers, which takes into account the varying form factors, size, and shape of smart watches, smartphones, laptops, smart TVs, and computer screens. Besides the app and the web, many other kinds of interfaces have been developed, including voice interfaces, touch interfaces, gesture interfaces, and multimodal interfaces.

The proliferation of technological developments has encouraged different ways of thinking about interaction design and UX. For example, input can be via mice, touchpads, pens, remote controllers, joysticks, RFID readers, gestures, and even brain-computer interaction. Output is equally diverse, appearing in the form of graphical interfaces, speech, mixed realities, augmented realities, tangible interfaces, wearable computing, and more.

The goal of this chapter is to give you an overview of the diversity of interfaces that can be developed for different environments, people, places, and activities. We present a catalog of 20 interface types, starting with command-based and ending with smart ones. For each interface, we present an overview and outline the key research and design considerations. Some are only briefly touched upon, while others, which are more established in interaction design, are described in greater depth.