What is the definition of expiry date? 

Expiration dates are not limited to edible products only. Credit and debit cards are also marked with exp dates.

Expiry dates are sometimes confused with best-before dates, but there is a definite distinction. Best-before dates inform consumers how long a product should be expected to stay fresh and may still be consumed even after that date has passed. Products with expiration dates are not to be consumed on or after the stated date.

Businesses use best-before dates to guarantee freshness and use exp. dates to communicate to consumers when last a product can no longer be used. These dates are required on products to meet consumer protection standards worldwide.