Consistency and Standards: Internal, External, and When to Break Them

Consistency keeps people from wondering whether two words or actions mean the same. Internal vs external consistency, Jakob's law, and when to break a rule.

info Quick Definition
Consistency and standards means that the same words, icons, and actions behave the same way inside the product, and in a way close to what the person already knows from other tools. The goal is that nobody has to wonder whether “Delete” and “Remove” mean the same thing.

What does this heuristic ask for?

NN/g includes it among its ten usability heuristics with a direct statement: users should not have to wonder whether different words, situations, or actions mean the same thing, and should follow platform and industry conventions (NN/g: 10 Usability Heuristics). The same article clarifies that the heuristics are broad rules of thumb, not specific guidelines.

The rule sounds obvious, but it is one of the most frequently broken. A team calls a button “Save” on one screen and “Confirm” for the same step on another. Another uses a three-line icon for the menu in one section and for filters in another. Each decision seems reasonable on its own. Together, they force people to learn the product again on every screen.

What is the difference between internal and external consistency?

NN/g distinguishes two types (NN/g: 10 Usability Heuristics):

  • Internal: staying coherent within one product or product family. Action names, control positions, and the meaning of colors should repeat.
  • External: following conventions established in the industry. A shopping cart with a recognizable icon, a search bar at the top, or a close button shaped as an X are examples.

Internal consistency is the direct responsibility of the team, and it is sustained by a design system and, in large organizations, by governance rules. External consistency depends on what people bring from other products.

What is Jakob’s law?

Jakob Nielsen proposes what is known as Jakob’s law of the internet user experience: people spend most of their time on other sites, so they expect yours to work the way the ones they already know do. Nielsen says he formulated it in 2000 (Jakob Nielsen: Jakob’s Law of the Internet User Experience).

His examples are everyday ones: search as a visible text box at the top, the shopping cart icon, visible scroll bars, or pinch-to-zoom on phones. Laws of UX presents it in the same spirit: users prefer your site to work the same way as all the others they already know (Laws of UX: Jakob’s Law). That is the practical reason external consistency matters so much.

When is it right to break a convention?

Nielsen is cautious. He notes that the law also applies to new interaction styles, such as voice, augmented reality, or AI, where standards are still forming. He argues that genuinely better innovations eventually become the new standard, and advises waiting until that happens unless you are willing to lose substantial traffic and revenue. His example of excess is scrolljacking, which hijacks scrolling and breaks the law (Jakob Nielsen: Jakob’s Law).

A practical rule: break a convention only if it solves a concrete problem the convention does not solve, if you test it with real people, and if you can explain the change in one sentence. If the only reason is that it looks different, do not break it.

How do you apply it without becoming boring?

Consistency does not require designing the whole product the same way. It requires that what repeats has the same name, the same place, and the same behavior. You can have a strong identity on the homepage and a very conventional checkout flow, because checkout is where surprising someone helps least.

Laws of UX suggests reducing the friction of change by letting people keep a familiar version for a limited time. In its 2017 redesign, YouTube let desktop users preview the new interface and switch back to the old one (Laws of UX: Jakob’s Law).

Illustrative example

Illustrative example: a project management app uses “Archive” to hide a finished project from the list, “Delete” to erase it forever from the detail view, and “Remove” on the members screen to take someone off a team. A user who learned the first meaning in the list does not understand the second in the detail view. The team reviews the microcopy and defines three verbs with rules: “Archive” hides and can be undone, “Delete” erases and asks for confirmation, and “Remove” takes a person out of a group. The change did not touch the visual design; it touched the coherence of the language.

If that coherence also applies to navigation patterns, review navigation patterns. And if the inconsistency shows up in search, the article on search UX explains how to keep autocomplete consistent with the rest of the site.

Common mistakes

  • Using two words for the same action on different screens.
  • Moving a main control between sections.
  • Breaking an industry convention for aesthetic reasons, such as hiding the shopping cart.
  • Building similar components with different behavior instead of reusing one.
  • Changing the meaning of a color or icon without warning.
  • Confusing consistency with monotony: a strong identity can coexist with clear conventions.

What you can do tomorrow

  1. List the ten action verbs in your product and check that each one means only one thing.
  2. Check where your search, cart, or profile sit. If they move between screens, choose one fixed position.
  3. Before breaking a convention, write the sentence that justifies the change and test it with two people.

Sources

Frequently asked questions

What does the consistency and standards heuristic say?
According to NN/g, users should not have to wonder whether different words, situations, or actions mean the same thing, and should follow platform and industry conventions.
What is internal vs. external consistency?
Internal consistency means staying coherent within one product or product family. External consistency means following conventions established in the industry or in other products the person already uses.
What is Jakob's law?
It is Jakob Nielsen’s idea that people spend most of their time on other sites, so they expect yours to work the way the ones they know do. Nielsen says he formulated it in 2000.
When is it right to break a convention?
When the innovation solves something clearly better. Nielsen advises waiting for an improvement to become standard, unless you are willing to lose substantial traffic and revenue. Changes should be tested with users.