Visibility of system status

Visibility of system status states that a good system should always keep users informed about what's happening and provide relevant and timely feedback for their actions.

Knowing a system's status gives users control over the situation and helps them understand where they are now and what they can do next. Appropriate feedback lets users know that their action (like a button click) is received and processed. Otherwise, users feel lost and confused — "Did I hit the button, or should I do it again? Is my file uploading, or has something gone wrong?"

The most common examples of system feedback include a change of color, an animated progress tracker, sound, slight vibration (on mobile), or a notification. For example, after users fill in all data, a Submit button changes its state from disabled to active, so users know the form is ready to be submitted.

Immediate feedback for interactive events allows users to detect errors and fix them quickly or even prevent them. For example, an inline error message on a password field saying Caps Lock is on helps users save time before hitting the Save button and encountering an error.