In 1993, Jakob Nielsen published his book Usability Engineering. It contains a list of ten short guiding principles, the Usability Slogans. They condense key findings from usability research into memorable statements. These principles date back to a time before smartphones, app stores, and the cloud – yet the mistakes they warn against still occur in product development today.
Nielsen wrote both of these word for word. The contradiction is only apparent – the resolution is in the section "The user paradox".
Usability refers to the practical functionality of a product, not its visual appearance. Steve Krug describes it like this: „Usability is about people and how they understand and use things, not about technology." Poor usability has measurable consequences: more support requests, higher bounce rates, and lower acceptance. The following ten slogans identify the most common causes.
Table of Contents
Background
Who Nielsen was and what the slogans are for.
The ten usability slogans
An overview of all ten, followed by an explanation by topic.
From slogan to practice
The iterative process and why early testing saves costs.
Common misconceptions
Five widespread assumptions – and the arguments against them.
Background
Jakob Nielsen, who later co-founded the Nielsen Norman Group, summarises the key messages of his book in a section titled "Usability Slogans". The purpose is practical: to formulate research findings in a way that keeps them present in day-to-day project work – during sprints as well as in discussions with stakeholders.
The slogans are neither a method nor a strict set of rules. They help to identify recurring misconceptions early on. For those who want to delve deeper into the topics: a video series explains the slogans in detail.
Usability is the practical functionality of a product: do users achieve their goal – quickly, without errors, and without unnecessary hurdles? The crucial point is that this can be measured: via success rate, task time, and error rate. Therefore, usability is not a matter of taste, but an engineering discipline.
The ten usability slogans
First, an overview, followed by an explanation by topic group. Each slogan is also provided in the original English, exactly as Nielsen formulated it.
| Slogan | Nielsen's key message | What it means today |
|---|---|---|
| "Your best guess is not good enough" — Your Best Guess Is Not Good Enough | Assumptions about users are unreliable. | Test instead of guess; even small sample sizes are informative. |
| "The user is always right" — The User Is Always Right | Users' problems are real problems. | A drop-off in the funnel is a design flaw, not a user error. |
| "The user is not always right" — The User Is Not Always Right | Proposed solutions are often wrong. | Observe behaviour rather than simply asking what people want. |
| "Users are not designers" — Users Are Not Designers | Identifying needs is not the same as designing solutions. | Feedback is a hint, not a final specification. |
| "Designers are not users" — Designers Are Not Users | The team is not representative of the target audience. | Your own routine is no benchmark for a first-time user. |
| "Vice presidents are not users" — Vice Presidents Are Not Users | Hierarchy does not replace data. | Tie decisions to evidence, not to the highest job title. |
| "Less is more" — Less Is More | More features create more complexity. | Focus makes things easier to find and use. |
| "Details matter" — Details Matter | Minor flaws add up. | Microcopy, load times, and error messages are anything but trivial. |
| "Help doesn't" — Help Doesn't | Help texts are rarely read. | Make the interface itself understandable instead of retrofitting help. |
| "Usability engineering is process" — Usability Engineering Is Process | Usability is a method, not a final state. | Measure and improve iteratively throughout the entire lifecycle. |
Data instead of assumptions
Three slogans address the same mistake: assumptions about users are treated as verified knowledge. "Your Best Guess Is Not Good Enough" contradicts this. Even experienced teams often misjudge how people use an interface – not out of incompetence, but because they can no longer view their own product objectively.
The third slogan in this group is "Vice Presidents Are Not Users" – executives are not users either. Even board members use the product differently from the actual target audience. A decision does not become correct simply because it comes from the most senior person in the room. In short: if a usability test shows something different from the consensus in the meeting, the test is what counts.
| Feature | Assumption ("Best Guess") | Evidence (Usability Engineering) |
|---|---|---|
| Foundation | Opinion, experience, gut feeling | Observed behaviour of real users |
| Guiding question | "What would I do?" | "What do the users actually do?" |
| Who decides | Whoever is loudest or highest in rank | The test result, not the position |
| Typical risk | Expensive correction after launch | Early, cost-effective iteration |
The user paradox
This is where the two statements from the introduction are resolved. "The User Is Always Right" means: when users fail, it is a real problem – specifically, a problem with the product. Steve Jobs formulated the same thought: „If a user is having a problem, it's our problem." An abandoned checkout is not an operating error, but a design problem.
"The User Is Not Always Right" adds the caveat: users reliably identify problems, but frequently suggest the wrong solution. Nielsen therefore advises: „Pay attention to what users do, not what they say." If you only ask users what they want, you end up building past their actual needs. If you watch what they do, you get far more reliable clues.
What matters: Taking users' problems seriously.
- Every drop-off and every moment of confusion is a valid signal.
- Complaints are data, not noise.
- The responsibility lies with the product, not the person.
Consequence: Systematically record and eliminate points of friction.
Clearly separating roles
Two contrasting slogans warn against the two most common fallacies. "Users Are Not Designers": Users can pinpoint exactly where the issue lies – but a ready-made solution does not automatically follow. A feature request is a hint, not a specification.
"Designers Are Not Users": People who work on a product every day lose their sense of how it feels to a first-time user. What seems obvious to the team is often a hurdle for the target audience. Frank Chimero formulated the consequence like this: „People ignore design that ignores people."
Users deliver problems
Their strength lies in highlighting real hurdles. Collect these signals – and translate them into solutions yourself.
Teams have blind spots
Routine creates tunnel vision. Regularly seek an unbiased external perspective.
Reduction and diligence
Three slogans concern the actual design. "Less Is More": Every additional feature and control element increases cognitive load and distracts from the essentials. More options do not lead to more satisfaction.
"Details Matter" is the necessary addition: reduction does not mean negligence. An unclear error message, a long load time, or an ambiguous label add up to frustration and drop-offs.
"Help Doesn't": In practice, help texts and tutorials are rarely read. An FAQ entry documents a usability problem; it does not fix it. Golden Krishna pointedly phrased the goal: „The best interface is no interface." This refers to an interface that is understandable without any additional explanation.
Before writing a help text, check whether the interface can be adjusted in a way that makes the explanation redundant. This is often possible.
Usability is not a state, but a process
The tenth slogan summarises the rest: "Usability Engineering Is Process". Usability is not achieved through a one-off rework at the end, but through a repeated cycle of understanding, designing, testing, and measuring – throughout the entire lifecycle of a product.
Usability engineering as an iterative cycle – not as a one-off final inspection
From slogan to practice
There is a well-documented economic reason for this process: the later a usability problem is discovered, the more expensive it is to fix. A change to a prototype takes minutes. The same change after launch costs far more – in development, testing, and migration.
Schematic representation of the well-documented software engineering principle of rising correction costs across project phases. The specific factors vary depending on the project – but the trend is constant.
The greatest leverage therefore lies early in the process. The effort involved is smaller than most people assume: as few as five test participants uncover the majority of serious usability problems – one of the best-known findings from Nielsen's work. A laboratory or a large panel is not required for this.
Understand the context of use
Prototype early and cost-effectively
Test with real users
Measure, don't opine
Iterate
Good usability lowers support efforts, increases acceptance and conversion, and reduces subsequent rework. Dr. Ralf Speth names the flip side: „If you think good design is expensive, you should look at the cost of bad design."
Common misconceptions
The following statements sound plausible, but regularly lead to poor decisions. The counterargument is provided alongside each.
Conclusion
Nielsen's slogans are over thirty years old and still applicable. They can be condensed into three basic principles:
1. Evidence over opinion
Your best guess is not good enough, and the highest job title does not replace data. Test instead of guess.
2. Reduction over abundance
Less is more, details matter, help doesn't. The interface should be self-explanatory.
3. Process over polish
Usability is a loop, not a milestone. Measure early, regularly, and with real users.
This also resolves the apparent contradiction from the beginning: take your users' problems seriously, but do not adopt their proposed solutions without vetting them first. This determines whether a product is actually used – or not.
If you would like to know where your product is losing users, we can support you with usability testing, analysis, and implementation. Contact us.