Warmth
Bacteria will multiply very quickly in the temperature range 5°C to 63°C This is known as the Danger Zone. Bacteria will grow very well at room temperature or even better at body temperature of 37°C. Hence, it is very important to keep food refrigerated or frozen, heat it to kill bacteria or hold it at a temperature above 63°C to prevent bacteria from growing. Most bacteria are destroyed at temperatures above 75°C.