food with a use-by date spoil rapidly and are not safe to eat after the date.
E.g. chicken, dairy, fish
Best before dates
food with a best before date will be safe to eat for a short while after the date and the quality will not be affected. However, the food quality will eventually reduce.
e.g. biscuits, dry pasta
Perishable foods
spoil easily and quickly
need to be stored in a temperature controlled environment
have a use by date
Ambient foods
can be stored at room temperature
have a best before date
can be semi-perishable food (limited shelf-life e.g. some bread, onions etc.)
Frozen foods
can be kept frozen for a few months
Meat and fish are perishable when defrosted, most bacteria becomes active once defrosted.