The vast majority of expiration dates are completely bogus - here's how long your food is still good
But most expiration dates are largely made-up. According to The National Resource Defense Council, the "sell by" dates do indicate not whether or not foods are safe to eat - they simply tell you when food will reach its limits for "optimal quality."
Handy website StillTasty compiles data from sources like the USDA, the FDA, and the US Centers for Disease Control and Prevention, as well as food manufacturers themselves. The site provides helpful tips on when to dispose of hundreds of household goods.