What Is User Interface Design? A Guide for Business Owners

User interface design is the work of shaping everything people see and interact with on a website or app: layouts, navigation, buttons, forms, text, colours, icons and the feedback the interface gives when someone acts. Good user interface design makes the next step obvious, so visitors find what they need, complete tasks without thinking about the interface and trust the business behind it.

Poor design hides important actions, overwhelms people with choices or behaves unpredictably, and visitors quietly leave. For a business, UI design is not decoration; it is a direct influence on enquiries, sales and support costs. This guide explains the essentials in plain language, so you can brief designers well and judge their work with confidence.

We first published this article in 2022. This version focuses on what business owners need to know when commissioning or reviewing design work.

UI and UX: what is the difference?

The terms are often used together, and the work overlaps, but they describe different things.

In practice, good projects combine both. A beautiful interface on top of a confusing journey still fails, and a well-planned journey with a clumsy interface frustrates people at every step.

On smaller projects, one designer often does both jobs. On larger ones, researchers and UX designers map journeys while UI designers create the visual system. Either way, ask to see how the interface decisions connect back to what customers need.

The building blocks of an interface

• Navigation: menus, search and links that help people find their way.
• Layout: how content is arranged on the screen and how it adapts to different sizes.
• Typography: readable fonts, sizes and line lengths that make text comfortable to read.
• Colour: used to show brand, highlight actions and signal status, with enough contrast.
• Controls: buttons, links, form fields, menus and toggles.
• Imagery and icons: photos, illustrations and symbols that support the content.
• Feedback: messages, loading states and confirmations that show what happened.

Each block can be designed well or badly, but the overall impression comes from how consistently they work together. A site with ordinary components used consistently often feels more professional than one with striking components used in a different way on every page.

Principles of good user interface design

Clarity

People should understand what a page is for and what they can do within seconds. Use plain labels, such as "Get a quote" rather than "Submit", and remove elements that do not help.

Clarity also applies to language. Write headings and buttons in the words customers use, not internal jargon. A visitor looking for prices should find a link called "Prices", not "Investment options".

Visual hierarchy

The most important content and actions should stand out through size, position, colour and spacing. If everything is emphasised, nothing is.

A useful test is to blur your eyes, or look at a screenshot from across the room. The elements you notice first should be the ones you most want visitors to see.

Consistency

Buttons, colours, icons and wording should behave the same way everywhere. Consistency lets people learn the interface once and use it confidently.

Consistency with familiar conventions matters too. Visitors expect the logo to link to the home page, the basket to sit at the top right and underlined text to be a link. Breaking these habits for the sake of originality usually costs more in confusion than it gains in style.

Feedback

Every action should produce a visible response: a button that shows it is working, a confirmation after a form is sent, a clear message when something goes wrong and how to fix it.

Speed is a form of feedback as well. A page that responds instantly feels reliable; one that pauses without explanation makes people tap again, refresh or give up. Show progress for anything that takes more than a moment.

Forgiveness

People make mistakes. Good interfaces make them easy to undo, ask for confirmation before destructive actions and never lose what someone has typed.

Error messages are part of this. "Invalid input" helps nobody; "Enter a phone number with your country code, for example +91 98765 43210" tells people exactly what to change. Well-written messages reduce abandoned forms and support calls at the same time.

Designing for phones first

Many visitors to business websites and stores arrive on phones, often with one hand and limited attention. Designing for the small screen first forces focus on what matters, and the larger layout can then add space and detail.

• Make buttons and links large enough to tap accurately with a thumb.
• Keep the main action visible without long scrolling or hunting.
• Use readable text sizes that need no zooming.
• Avoid pop-ups that cover the content on small screens or are hard to close.
• Test on real devices, not only in a desktop browser, including older and smaller phones.

Our guide to mobile UX mistakes lists the problems that most often cost online stores sales on phones.

Accessibility is part of user interface design

An accessible interface works for people with a wide range of abilities, including those who use screen readers, keyboards, magnification or voice control. It also helps everyone else: clear contrast helps in bright sunlight, and captions help in noisy places. The W3C's accessibility fundamentals explain the principles, and the Web Content Accessibility Guidelines give a testable standard.

• Sufficient colour contrast for text and controls.
• Every form field has a visible label.
• Everything works with a keyboard, with a visible focus indicator.
• Images have meaningful alternative text.
• Information is not conveyed by colour alone.

Our guide to accessibility for online stores covers the requirements in more depth.

UI design for online stores

Stores have particular interface needs, because every screen sits somewhere on the path to a purchase.

• Category pages: clear filters, sorting and product cards with the information shoppers compare.
• Product pages: large images, prices, options, delivery information and a prominent add-to-basket button.
• Basket and checkout: few distractions, clear costs, simple forms and reassurance about payment.
• Account area: order history, reorders and addresses that are easy to find.

Our guides to product page best practices and checkout form design go into each stage in detail.

How to brief and review a designer

Good design starts with a good brief. Designers work best when they understand goals, users and constraints, not just preferred colours.

1. Explain the goal: more enquiries, more online sales, fewer support calls.
2. Describe the users: who they are, what devices they use and what they are trying to do.
3. Provide real content: actual text, products and images, so designs reflect reality.
4. Share constraints: brand guidelines, platform limits, budget and deadlines.
5. List examples you like and dislike, with reasons.

When reviewing designs, judge them against tasks rather than personal taste. Ask: can a new visitor find the main action in five seconds? Can a customer complete the key task on a phone without help? Short tests with a handful of real users often reveal more than long internal discussions.

Give feedback in terms of problems rather than solutions. "Customers may not notice the delivery information" is more useful to a designer than "make the text red", because it lets them find the best fix within the design system.

Design systems: consistency over time

A website rarely stays the same for long. New pages, campaigns and features are added by different people over months and years, and without a shared reference the interface slowly becomes inconsistent. A design system prevents that drift.

• Components: a library of reusable buttons, forms, cards, navigation and messages, each designed once.
• Styles: agreed colours, fonts, spacing and icon rules, with accessible contrast built in.
• Patterns: standard solutions for common tasks, such as how errors appear or how filters behave.
• Guidelines: short notes on when to use each component and when not to.
• Code to match: the same components implemented in the website or app, so design and build stay aligned.

Even a small design system, a single page of components and rules, saves time on every new page and keeps the experience familiar for customers. It also makes it easier to change suppliers, because the next designer or developer can see exactly how the interface is meant to work.

Common UI mistakes

• Too many competing calls to action on one screen.
• Low-contrast grey text that is hard to read.
• Icons without labels whose meaning is unclear.
• Forms that ask for unnecessary information.
• Carousels and animations that distract from the content.
• Designs approved on large monitors but never tested on phones.
• Important information placed in images, where it cannot be read by screen readers, translated or found by search engines.

Frequently asked questions

Want an interface that helps visitors become customers? Talk to our team about design, or see our e-commerce design services.