01 / THE IDEA
What does it mean?
A component's states express interaction and system status: default, hover, focus, loading, disabled, error, and success.
02 / IN PRACTICE
Make it concrete.
Illustrative example: A Save button shows a loading state and then changes to “Saved” only after confirmation.
03 / WHAT TO WATCH FOR
A common mistake.
Shipping a pristine default state but forgetting errors and loading.
04 / WHEN IT HELPS
When should you use it?
When defining reusable UI components and developer handoff.
05 / FURTHER READING
Explore the source.
Nielsen Norman Group — Visibility of System Status ↗A reference for further learning, not an endorsement or verbatim quotation.