Understanding UI design and its principles

6 min read Max Koh

Wireframes. Mockups. HTML. Fonts. Elements. Users. If you’re familiar with user interface design, these terms will be your bread and butter.

An integral part of any website or application, user interface design is also arguably one of the most important. This is because your design is what your users see and interact with. If your site or app functions poorly and looks terrible, that’s what your users are going to remember.

But isn’t UX design and UI design the same thing? Or is there just an extremely blurred line between the two? What’s involved with UI design and, more importantly, what makes good design?

What is UI design exactly?

If you’re wondering how to test UI on your website, it’s a good idea to first learn some of the differences between UX and UI design. Although UI design and UX design look similar when written down, they’re actually two totally separate things. However, they should most definitely complement each other.

UX design, according to Nielsen Norman Group, “encompasses all aspects of the end-user’s interaction with the company, its services, and its products.” Meanwhile, UI design focuses more on a user’s interaction, the overall design, look and feel of a system. The two still sound similar, right?

For those of you still trying to wrap your ahead around the difference, Nielsen Norman Group has a great analogy up on its site that helps to explain it: “As an example, consider a website with movie reviews. Even if the UI for finding a film is perfect, the UX will be poor for a user who wants information about a small independent release if the underlying database only contains movies from the major studios.” This just goes to show the complementary relationship between the two and why it’s so important.

User interface was popularized in the early 1970s, partly thanks to Fuji Xerox’s ‘Xerox Alto Workstation’ — an early personal computer dubbed “the origin of the PC”.

This machine used various icons, multi windows, a mouse, and e-mail, which meant that some sort of design and design principles were needed to create consistency for the future. It was here that human-centred UI was born.

UI design also covers graphical user interface design (GUI design). A GUI is the software or interface that works as the medium between a user and the computer. It uses a number of graphical elements, such as screen cursors, menus, and icons so that users can easily navigate a system. This is also something that has stemmed from Fuji Xerox back in the late 1970s and early 1980s.

Since then, UI has developed quickly and so has its design principles. When the Xerox Alto Workstation was first born, Fuji Xerox came up with eight of its own design principles. These were:

  • Metaphorically digitize the desk environment
  • Operating on display instead of entering on keyboard
  • What you see is what you get
  • Universal but fewer commands
  • Same operation for the same job at different places
  • Operating computers as easily as possible
  • No need to transfer to different jobs
  • System customized as desired by users

Over time, these principles have evolved and now you’ll likely find many more added to this list. Here are just a few of the most important ones identified in “Characteristics of graphical and web user interfaces” by Wilbert Galitz.

UI design principles:

Principle #1: Clarity

Usability.gov says that the “best interfaces are almost invisible to the user”.

Everything in the system, from visual elements, functions, and text, needs to be clear and simple. This includes layout as well as the words used — stay away from jargon and complex terms or analogies that users won’t understand.

Aesthetic appeal also fits into this principle. Ensure colors and graphics are used in a simple manner, and elements are grouped in a way that makes sense.

Principle #2: Consistency

The system should have the same or similar functions, uses and look throughout it for consistency. For example, the same color scheme should be used throughout an app, or the terminology on a website should be consistent throughout. Users should also have an idea of what to expect when they use your system. As an example, picture a retail shopping app. You’d expect that any other retail shopping app out there will have similar basic functions: a place to log in or create an account, account settings, a way to navigate and browse stock, a way to purchase stock at the press of a button. However, this doesn’t mean copying another app or website exactly; there should just be consistency so users know what to expect when they encounter your system.

Apple even states an “app should respect its users and avoid forcing them to learn new ways to do things for no other reason than to be different”.

Principle #3: Flexibility and customizability

Is there more than one way people can access your system and its functions? Can people perform tasks in a number of different ways, too?

Providing your users with a flexible system means people are more in control of what they’re doing. Galitz mentions this can also be done through allowing system customization.

Don’t forget use on other kinds of devices, too. In a time when Google is using mobile-friendliness as a ranking signal, and research from Ericsson shows smartphones accounted for 75% of all mobile phone sales in Q4 2015, you know that being flexible is important.

Examples of good UI design

For a list of some of the best user interface examples, check out last year’s Webby Awards category for Best Interface Design. The 2016 category winner was the Reuters TV Web App, while the People’s Choice winner was AssessYourRisk.org.

As an aside, this is the second year that the Webby Awards introduced this category — just goes to show how important it is to have good UI design!

While you don’t want your site or application to look exactly the same as these winners, you still want yours to function well and be aesthetically pleasing. To help you get there, there are a number of UI design tools and UI software available.

Here’s a list of some of the many out there:

  • UXPin – An online UI design tool that allows you to create wireframes, mockups, and prototypes all on one platform.
  • InVision – A prototyping and collaboration tool. More in-depth than Balsamiq, and it allows you to go from mockup to high-fidelity in minutes.
  • Balsamiq – A simple mockups tool for wireframing, which allows users to test out ideas in the early stage of interface design.
  • Atomic – An interface design tool that allows you to design in your browser and collaborate with others on your projects.

Have you got any favorite UI design examples, or tips for beautiful design? We’d love to see them — comment below and let us know!

Further reading:

Published on May 10, 2016

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Max Koh

Max is Optimal Workshop’s UX writer, resident cat whisperer and Samoyed enthusiast.