The most common User Interfaces (UIs)

It is important to understand evolution of the computer and the interfaces over the past 4-5 decades. In the 1970’s, to use a computer, the command line interface was used-in which users needed to communicate via programming language, requiring seemingly infinite lines of code to complete a simple task. Graphical interfaces didn’t exist commercially. In the 1980’s Xerox PARC developed the first graphical user interface (GUI), wherein users could interact with their personal computers by visually submitting commands through icons, buttons, menus, and checkboxes. No coding was required, and it initiated the personal computer revolution. By 1984 Apple Computer released the Macintosh personal computer which included a point and click mouse- the first commercially successful home computer to use this type of interface. If users couldn’t interact with their computers, they wouldn’t sell. As a result, the UI designer was born.

In today's high tech age, the UI designer has nearly limitless opportunities to work on websites, mobile apps, wearable technology, and smart home devices. The UI designer’s role has evolved as systems, preferences, expectations, and accessibility put extreme demands on devices, and the need increases to make interfaces that enable users of all ages, backgrounds, and technical experience can effectively use. Today's UI designers work on computer interfaces, mobile phones, augmented and virtual reality, and even screen-less interfaces (zero UI) like voice, gesture, and light. Prototyping and simulation are the primary interface design techniques. A prototype is created based on requirements from ideation sessions and interaction specifications. Simulation is a part of validating design decisions by testing a prototype with people that represent the target audience. It is an essential part of usability testing sessions, wherein the product team gives participants a prototype and a predefined set of tasks and see problems faced during the interaction.

Three most common UIs:
Command Line interface: Used previously, these interactions were linear – the user (operator) typed a command, and the machine responded to the command either using printed output or by displaying a message on the monitor. Users had to know machine language to interact with computers, adding to the complexity of such interactions.
Graphical User Interface: Allows users to interact with digital products through visual elements, as they go through a series of pages or screens. Those pages/screens contain static elements (such as text sections) and active elements (such as buttons and other interactive controls). Examples- Mobile devices, VR headsets, and Car HMIs. The problem with GUIs is the steep learning curve, every time users interact with a new product.
Voice-based Interface: Is considered the closest to zero UI is voice-enabled interfaces, which allow the user’s voice to interact with a system. Recent progress in natural language processing (NLP) made it possible to design smart AI-powered systems.