Freezer burn is the patchy, pale, dry discoloration that appears on frozen food when moisture evaporates from its surface into the dry air of the freezer — essentially surface dehydration. It strikes food that is poorly wrapped, stored too long, or subjected to temperature fluctuations that let ice crystals migrate and sublimate. The affected spots turn tough, leathery, and off-flavoured as fats oxidise, though the food remains safe to eat; trimming the damaged areas usually salvages the rest. Prevention is straightforward: wrap food tightly in moisture-proof packaging, expel air before sealing, keep the freezer at a steady −18 °C or below, and respect sensible storage times. Vacuum packing is the most reliable defence.