Consistency and standards
Making the same words, controls, and actions behave the same everywhere, while respecting conventions people already know.
See it
What it is
Consistency and standards is Nielsen's fourth usability heuristic: people should not have to wonder whether different words, icons, or actions mean the same thing. Internal consistency makes one product predictable; external consistency follows conventions people learned from the platform and other products: underlined links, Cmd+Z for undo, and window controls at the top left on macOS but the top right on Windows. Jakob's law is the blunt version, and it is also Nielsen's: people spend most of their time on other products, so they expect yours to work like those.
Reach for it when defining components, naming actions, or joining flows built by different teams. One design-system button, one label for each action, and one response to the same input let learning transfer from the first screen to the fiftieth.
Gotcha: consistency is not copying a bad pattern forever. A convention can be inaccessible, misleading, or wrong for a new context. Break it when the benefit is clear, but make the new behavior visible, teach it once, and apply it coherently instead of producing a special case that only its designer understands.
Ask AI for it
Audit this interface for consistency and standards. Inventory every button, link, menu, dialog, form field, and status message, then group controls that perform the same action and identify mismatched labels, icons, placement, keyboard behavior, or feedback. Replace duplicates with shared shadcn/ui Button, Dialog, DropdownMenu, and Form components, use one verb for each action across the product, preserve native browser conventions for links and form submission, and return a table of each inconsistency and the standard component or wording that fixes it.