With all the talk about food safety these days, we've all become more vigilant about food expiration dates. Should you toss pasta past its "best before" date? What about fresh milk when its "use by" date is yesterday? Believe it or not, these dates and labels don't have standard definitions -- here's what they really mean.

Best before

The "best before" date is an indication of a product's optimal quality or flavor, not its safety. "The product can still be eaten within a reasonable time after this date, but the manufacturer can no longer guarantee the quality of the foodstuff," explains registered dietician Karen Protheroe. For example, crackers lose their crispness beyond the "best before" date, but they remain safe for consumption.

Use by

Take this date literally. "Use by" dates are stamped on highly perishable products like meat, milk and fish, so safety and spoilage are a major concern. Don't eat food beyond the "use by" date, says Protheroe. If you do, it's at your own risk.

Sell by

Foods past their "sell by" dates are still safe to eat, so don't toss them just yet! "This is an indication for the staff of the retailer who is selling the food, of the date by which the product should be sold, so that the consumer still has some time during which to eat the product," adds Protheroe.

No date

If there is no date stamped on a product, let your nose and taste buds be your guide. If you're unsure, it's better to err on the side of caution and chuck it out.