The three-digit code (001–365) on egg cartons marks the day of the year they were packed, while “P” numbers identify the processing plant and dates like “Sell By” or “Best By” indicate inventory timing and peak quality rather than definitive safety. Because bacteria like *Salmonella* cannot be detected by sight, smell, or even the floating test—which only reflects an egg’s age—safely managing eggs relies on keeping them in their carton at 40°F (4°C) or below for three to five weeks, avoiding cracked shells, cooking until yolks and whites are firm, and discarding any improperly stored or compromised eggs.READ MORE BELOW