Consistency and Standards
Use the same words and patterns for the same things, then follow conventions people already know.
Consistency lets people reuse what they already know.
A button says Save on one screen and Store on another. They may do the same thing, but now the user has to stop and check. Consistency removes that question by giving the same action the same name, look, and behavior.
Origin
Jakob Nielsen included Consistency and Standards in his 1994 set of usability heuristics. Rachel Krause later described two layers: consistency within a product and consistency with familiar web, platform, and industry conventions.
Use the same name for the same action everywhere. Save, Store, and Apply should not be interchangeable unless they do different things.
Give repeated components the same appearance and behavior. A primary button should not change meaning from one screen to the next.
Follow familiar conventions for navigation, search, carts, forms, and other common interactions. People should not have to learn a private language for your product.
Break a convention only when it serves a clear need. Test the new pattern because every unfamiliar interaction asks people to learn something new.
Digital systems
Microsoft Office Ribbon
Word, Excel, and PowerPoint each use the Ribbon. The available controls vary, but shared tasks such as formatting text use a familiar layout across all three products.
Physical signals
Hotel Check-in Desk
Hotel check-in desks are usually near the entrance, where arriving guests expect to find them. Keeping that familiar placement removes the need to search or ask where to begin.
When the same action looks or behaves differently across a product, people stop to interpret it again. The interface makes them relearn something they thought they already understood.
Keep names, components, and behaviors consistent within the product. Follow familiar platform conventions, and make exceptions only when research shows that the new pattern works better.