What is cross-contamination of foods?

The term cross-contamination of foods refers to the unintentional transfer of microorganisms or chemical substances from one food to another. The transfer can occur directly, when two foods come into physical contact or one drips onto another; or indirectly, through intermediate vehicles such as work surfaces, cooking utensils, or the hands of the person handling and preparing the food.
To find out in detail how cross-contamination works, watch this video produced by the Istitituto Zooprofilattico Sperimentale delle Venezie (IZSVe), an Italian health authority and research organization in the fields of animal health, food safety and zoonoses.