Generally, you'll see three types of expiration dates on your food, and they all mean slightly different things. However, contrary to popular belief, they refer to the quality of the food, not the safety. Here's what each one means: 1  Sell By: This date tells the store how long to keep the item on their shelves. 2  If it reaches the date before its sold, the store will pull it from the shelves. 3  It represents the last day the food is at its peak quality of freshness, taste, and consistency.