UX Design Principles Explained: 10 Usability Heuristics, Accessibility and Salesforce Examples (2026)

Hey friends,

UX design principles are guidelines for making interfaces easy to understand, efficient and fair to use. The ten usability heuristics from the Nielsen Norman Group (NN/g) are the most cited set, Salesforce's design system adds four of its own (clarity, efficiency, consistency and beauty), and accessibility rests on four principles: perceivable, operable, understandable and robust. If you can recognize each in a real screen, you're set for UX Fundamentals (16%) and Human-Centered Design (12%) on the Salesforce Platform UX Designer exam.

Here's each set, with Salesforce examples. The heuristics come from NN/g's 10 usability heuristics, and the examples are my own.

What are the 10 usability heuristics?

Don't memorize the list as a poem. Practice spotting which heuristic a bad design breaks. A form that wipes your entries after an error breaks user control. A cryptic "Error 4021" breaks error recovery.

What are Salesforce's design principles?

The Lightning Design System guidelines name four principles that guide design decisions at Salesforce:

They overlap with the heuristics: consistency is heuristic 4, and efficiency is heuristic 7. I go further into the design system in my SLDS post.

If you learn best by testing yourself, the Platform User Experience Designer Cert Lab has quick practice questions on UX fundamentals and accessibility, with every option explained.

What are the four principles of accessibility?

The Web Content Accessibility Guidelines (WCAG) are built on four principles, described in W3C's Understanding WCAG 2.2. Content must be:

How do you design for accessibility in practice?

These are the practical points Salesforce's UX Designer prep stresses:

• Use enough contrast between adjacent colors, so people with visual challenges can tell them apart.
• Never use color as the only way to show meaning. Add text or an icon next to a red or green dot (WCAG success criterion 1.4.1).
• Build a real heading structure. Screen reader users commonly navigate by headings.
• Make everything reachable by keyboard, with a visible focus indicator. Test with both a keyboard and a screen reader.
• Let people pause or stop animation that lasts longer than 5 seconds (success criterion 2.2.2), and avoid anything that flashes more than 3 times per second (2.3.2).
• Treat icons properly: a screen reader skips decorative icons but not informational ones, which convey content.

Accessibility also guides how you test. WCAG's own guidance recommends including users with disabilities in test groups, not just running checkers.

What is inclusive design?

Inclusive design means considering the full range of people who will use what you build, not an imagined average user. In Trailhead's Human-Centered Design unit, relationship design extends the usual human-centered design checks of desirability, feasibility and viability with inclusivity, sustainability and ethics.

What mistakes do people make with UX principles?

• Treating heuristics as laws. They're rules of thumb, so use them to find problems, then test with users.
• Using jargon from your team's internal process in field labels and messages.
• Showing every field to every user instead of what's relevant to their task.
• Adding accessibility at the end instead of in the first wireframe.
• Using color alone for status.
• Customizing standard patterns so users have to relearn them.

How does this show up on the Salesforce exam?

UX Fundamentals scenarios ask for the principle or tool behind a design choice, such as contrast, user flow and responsive layout. Human-Centered Design asks about inclusive design. If a question gives you a screen problem, name the principle it breaks, then pick the fix that restores it.

Quick backstory. I loved Focus on Force and used it on my way to 17 Salesforce certifications. At first I read the study guide cover to cover, then took the tests. What I eventually noticed: I learned way faster when I skipped ahead and took practice tests rapid-fire, reading the explanation for every miss. So I built Cert Lab around fast testing, with up-to-date doc links in every explanation. It's designed to test you to success.

FAQ

What are the 10 usability heuristics?

Visibility of system status; match between the system and the real world; user control and freedom; consistency and standards; error prevention; recognition rather than recall; flexibility and efficiency of use; aesthetic and minimalist design; help users recognize, diagnose and recover from errors; and help and documentation.

What are Salesforce's four design principles?

Clarity, efficiency, consistency and beauty.

What are the four principles of accessibility?

Perceivable, operable, understandable and robust.

Can color be the only indicator of status?

No. WCAG asks for another cue, such as text or an icon, so people who can't distinguish the colors still get the information.

Is accessibility on the Salesforce UX Designer exam?

Yes. The UX Fundamentals objectives include design principles and tools for an accessible, engaging experience, and Human-Centered Design includes inclusive design.

Where should you go next?

• The Platform UX Designer study guide for the full outline.
• The Salesforce Lightning Design System for the SLDS section.
• Platform UX Designer practice questions.

Nick Frates, a senior Salesforce developer with 17 certifications, built the Platform User Experience Designer Cert Lab at nickfrates.com: rapid-fire practice questions for every exam section, each answer explained.

Hope this helps!

Best,

Nick