Confused by what date labels on food products mean? Us, too. So we looked into it.

Have you ever wondered what on Earth all of those "best before," "sell by," and "expiration" dates sprinkled on products actually mean?

Go into any grocery store, and you’ll be confronted with different dates on all kinds of food. Not only are there "best before" dates and "sell by" dates, there are also "harvest" dates and "shipping" dates, to name just a few.

If you’re simply trying to buy food that’s as fresh as possible, it’s hard to know what to pay attention to or what dates to trust.

Take "best before" labels, for example.

According to the Food and Drug Administration (FDA), food producers aren't required to put "expired by," "use by," or "best before" labels on their products, and if they do put an expiration date, FDA laws don't preclude the sale of food past it (with the exclusion of infant formula).

According to professional home economist Ellie Topp, most "best before" labels have nothing to do with food safety and everything to do with food taste. Food producers want to protect their brands, and ensuring their food is as delicious as possible is part of that. A package of noodles or a bag of tortilla chips eaten at a reasonable time after its "best before" date will most likely be perfectly safe to eat and taste the same. This is even true for eggs and dairy products.

Knowing that food labels aren't necessarily telling consumers what we think they are is one thing — actually using them to inform food-buying choices is another. Armed with my newfound label-reading skills, I hit up my favorite local grocery store for some necessities.

Here's what I learned, along with a few things you might want to keep in mind during your next trip to the grocery store:

1. Milk cartons usually display some iteration of a “sell by,” “best before,” or “freshest by” date, but the milk can last a lot longer than that if unopened.

The date on this carton of lactose-free milk tells the shelf stockers at my local grocery store that it is good to sell until Dec. 8 if it is refrigerated properly. When it comes to living in my fridge, pasteurized milk can last quite a while longer if it's unopened (and then at least a week after it's opened). Pasteurized milk is one of the safest products out there. As a general rule — as long as it smells and tastes OK, it's fine to drink. And if it starts to sour, you can make these pancakes.

2. When it comes to eggs, "sell by" or "best before" doesn’t mean "throw me out."

Most cartons of eggs purchased from grocery stores are fresh and delicious even after the "sell by" date. The FDA says to eat eggs within three-five weeks of purchasing them. The sell-by date will likely pass during that time, but the eggs are still safe. Older eggs may not taste as fantastic as eggs fresh from the farm, but they're also not likely to make you sick either.

If for some reason you’re skeptical about the health of your eggs, there’s an amazeballs little test you can try — and you only need a glass of water to do it! Plop a questionable egg into the glass of water and watch what happens. A fresh egg will sink to the bottom; a not-so-fresh will float.

3. Canned goods are the one true post-apocalyptic food.

In a famous zombie movie, the heroes sought out Twinkies as the perfect post-disaster food. Realistically, they should have been looking for canned goods. "Best before" dates on cans are to remind consumers of when the food inside them is still at its best. After that date, the food inside may lose some of its flavor but should still be safe to eat. As long as the cans aren't dented, swollen, or rusty, the USDA says they're "safe indefinitely as long as they are not exposed to freezing temperatures, or temperatures above 90 degrees."

Lack of clarity around food labels affects more than consumer food choices. It also has big implications for our landfills.

A 2013 study by the Natural Resources Defense Council found that confusing food date labels led to a lot of "perfectly good, edible food" being wasted in America. While most consumers were looking to date labels for information on food safety, the manufacturers were providing information about optimal food freshness instead. That difference is significant and can result in a lot of food being thrown out before it needs to be. According to their research, Americans throw out an average of $390 worth of food per person per year. For a family of four, that’s $1,560 per year — not to mention a lot of food going to waste unnecessarily in our landfills.

In an ideal world, choosing the safest, freshest food in the grocery store shouldn’t require a calendar or a cheat sheet.

Whether we realize it at the time or not, we’re putting a lot of thought into the food we bring into our homes and put on our plates. Coupled with education programs around food safety and waste, simple and standardized food labels could be a way of helping us make safer, fresher choices that keep still-good food out of landfills.

Until that happens, there’s always the sniff test.