Food and medicines may have dates on them. Those dates have different names and different meanings. This page will help you to understand what they mean and how they are different.
Best Used By Date (BUBD)
Use By Date (UBD)
The BUBD and UBD are the same, really. This is the date after which the product may not meet the same standard that it did when it was delivered. However, this does not mean it is dangerous to eat it. For example, if you cook and eat rice after the BUBD, it might not taste as good as it would have if you used it the first day you had it, and it may not have the full nutritional benefit. But it will not make you sick.
An Expiration Date, on the other hand, tells us the date after which a product cannot be used. After this date it could have changed enough to cause harm to the person who consumes it.