There's long been confusion around "sell by" and "best by" dates, not to mention the labels "best if used by," "use by," "expires on" and more. That's why the Food Marketing Institute and the Grocery Manufacturers Association have been trying to standardize how companies label their perishable foods. Until they're able to get all food vendors fully on board, though, here's some clarity around those terms and how important they really are.What is a "sell by" date? Unlike a lot of the other labels you see on food, the "sell by" label is primarily meant for the retailer, not the customer, the Institute of Food Technologists reports. "Display until" is the only other similar label; it indicates to retailers how long something should be on shelves.So can I not eat something after that date?You totally can. Products with "sell by" dates on them typically have about two-thirds of their life left in them still.Is "use by" similar? No! That said, though you should try to use whatever you bought by the date given, it won't necessarily kill you to push it a bit. The IFT says this is "a directive of the date by which the product should be eaten; mostly because of quality, not because the item will necessarily make you sick if eaten after the use-by date."All right, how about a "best by" stamp, then?This is the one you should really pay attention to. Anything reading "best by" is, well, best by the specified date. Sure, there are exceptions to the rule, but that's there so you generally don't eat anything spoiled. This is a quality issue above all else. If you see "best before," that means just about the same thing, FYI.So why isn't there just one standard label telling me when to eat stuff by?Excellent question! And that's exactly what the Food Marketing Institute and the Grocery Manufacturers Association have been working toward for years. They put forth a policy in 2017 that suggested and encouraged retailers to switch to exclusively using "best by" and "best if used by" as opposed to any of the other aforementioned labels. “Eliminating confusion for consumers by using common product date wording is a win-win because it means more products will be used instead of thrown away in error,” Jack Jeffers, vice president of quality at Dean Foods said at the time. “It’s much better that these products stay in the kitchen – and out of landfills.”They're hoping most big box retailers will be on board by 2020.