Freezing food preserves it from when it is prepared to when it is eaten. Since early times, farmers, fishermen, and trappers have preserved grains and produce in unheated buildings during winter. Freezing keeps food safe by slowing the movement of molecules, causing microbes to enter a dormant stage. Freezing preserves food for extended periods because it prevents the growth of microorganisms that cause both food spoilage and foodborne illness. Frozen food is any type of food that the processor has frozen and preserved, typically for sale in the frozen state. Processors freeze food to slow the decomposition of fresh food and prevent bacterial growth. This food can stay on shelves for months or years, while fresh food typically only lasts a few days.