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Counter
Counters contain dynamic number values. Counters help users quickly identify quantities of non-visible items.
Details

Default
Light
Dark
With Border
Best Practices
1
.
Numbers
Counters should only contain numbers.

Do
Use only numeric values

Don't
Use to indicate other information
2
.
Usage
Counters should have a clear connection to the non-visible items they represent.

Do
Position Counters within correct context

Don't
Seperate the Counter from associated entity
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Additional Reading
Indicators, Validations, and Notifications: Pick the Correct Communication Option https://www.nngroup.com/articles/indicators-validations-notifications/