Consistency and standards is Nielsen's fourth heuristic: users should not have to wonder whether different words, situations or actions mean the same thing. It has two halves. Internal consistency means one pattern per job inside your product, so a lesson learned on one screen carries to the next. External consistency means following platform and industry conventions, because people arrive with habits formed elsewhere (Jakob's Law).
On this site it shows up as good when an icon in onboarding matches the button on the home screen, or when every connector form uses the same layout. It shows up as bad when a setting defaults to on in one place and off in another, when copy refers to a plan name that does not exist, or when a "Run next step" button stays visible after all steps are done.
In paywalls and upsells, inconsistency costs trust directly. If the plan names, prices or feature lists on two screens do not match, people assume the product is careless or that something is being hidden, and they stop before paying.
How to use it
- Use one name for each plan, feature and action across onboarding, pricing, emails and the app; check them side by side before launch.
- Reuse the same form layout, button order and default values for similar tasks, so the second one feels familiar.
- Follow platform conventions for navigation, close buttons and system dialogs instead of inventing new ones.
Watch out
- Copying a convention that does not fit the task, just because competitors use it, can mislead people about what a control does.
- Imitating the look of a system dialog or another app's UI to borrow its trust is deceptive and can get an app rejected.
