User interface design

User interface (UI) design is the specialized process of creating interfaces for machines and software. Designers build these systems for computers, mobile devices, home appliances, and even cars or commercial planes. The primary focus of UI design is to maximize usability and the overall user experience. This involves building interfaces that clearly communicate what information is most important to a person. A successful interface allows a user to complete a task efficiently without drawing unnecessary attention to itself.

There are three main types of user interfaces used today. The first is the graphical user interface, or GUI, where users interact with visual representations on a screen, such as a computer desktop. The second type uses voice control, allowing users to interact with machines through speech. Examples include smart assistants like Siri on smartphones or Alexa on Amazon devices. The third type utilizes interactive gestures, where users interact with 3D environments using their bodies. This is common in virtual reality (VR) games.

To create these tools, designers often use a framework called design thinking. This modern framework was created in 2004 by David M. Kelley, the founder of Stanford’s d.school. The process is frequently described by the acronym EDIPT, which stands for empathize, define, ideate, prototype, and test. This process is non-linear, meaning designers may jump between different stages to refine their work. Through iteration, designers constantly tweak their designs to ensure the final product meets human needs.

The EDIPT process begins with the empathize stage. Designers conduct user research to understand the specific needs and pain points of their audience. They often use semi-structured interviews to gather qualitative data about user workflows and technical skills. Next, they move to the define stage, where they create a single-sentence problem statement. This statement must include the specific user, their need, and their desired goal. After defining the problem, designers enter the ideate stage to brainstorm potential solutions that are both desirable and feasible.

In the next phase, designers create prototypes. These are models of the design that can vary in fidelity, ranging from low to high. Prototyping is an iterative process where designers explore many different solutions rather than settling on the first idea. Finally, they reach the test stage. Designers present these prototypes to the actual target audience to gather feedback. This stage helps them understand how a viewer receives the design and allows them to improve the user experience before the final version is built.

Experts play a major role in shaping how we measure the quality of these interfaces. Jakob Nielsen and Don Norman co-founded the Nielsen Norman Group in 1998. Nielsen pioneered the usability movement and created the "10 Usability Heuristics" for design. Usability is defined by the ISO 9241 standard through three specific factors: effectiveness, efficiency, and satisfaction. Effectiveness measures how well a user achieves their intended goals. Efficiency measures the resources, such as time or effort, required to reach those goals. Satisfaction measures how acceptable the user finds the system.

Designers also use different methods to evaluate how well a system works. One method is usability testing, where researchers observe actual users interacting with a prototype. This often uses the "think aloud protocol," where users speak their thoughts during the process. Another method is usability inspection, which is often cheaper and used earlier in development. This includes the cognitive walkthrough, which focuses on how easily new users can complete tasks. It also includes heuristic evaluation, where experts use established rules to find problems, and pluralistic walkthroughs, where groups discuss task scenarios.

Finally, the ISO 9241 standard provides strict guidelines for the "feel" and "look" of an interface. The "feel" is described by seven dialogue principles, such as controllability and error tolerance. Controllability means the user can manage the pace and direction of the interaction. Error tolerance means a user can achieve their goal even if they make a mistake in input. The "look" is described by seven presentation attributes, including clarity, conciseness, and legibility. These attributes ensure that information is easy to read, distinguish, and understand without overloading the user with too much data.