Use by date (DLC in France)
A mandatory "use by" date shown on microbiologically highly perishable foods, after which the product must no longer be eaten for food safety reasons.
The use by date (DLC in France) is recognised by the wording « use by… », followed by the day, month and year. It applies to fresh, highly perishable products: meat, fish, charcuterie, chilled ready meals, some dairy products (yoghurts).
An original angle (the crucial distinction): the use by date is a safety limit, not a quality one. Beyond it, the risk is not about taste but microbiological (pathogenic bacteria such as Listeria and Salmonella). This is why shops cannot legally sell a product after its use by date.
These products must be kept in the fridge; the cold chain is essential. A use by date is calculated ASSUMING that chain is respected. A yoghurt left for 3 hours in a hot car can be dangerous even before its use by date.
Not to be confused with the best before date (DDM in France), which is only indicative. This confusion is a major source of food waste: many people throw away perfectly safe products because they think a passed best before date is dangerous.
A caveat: some products with a use by date can be frozen before the date to extend their life, in a way resetting the clock (but they should be eaten soon after defrosting).