Cross contamination

You must prevent raw and cooked foods touching each other.
If raw and cooked foods touch each other then bacteria pass between them.
You must not allow meat to drip onto other foods as this will contaminate the food.
You must also prevent bacteria from being transferred on hands, chopping boards, surfaces and other utensils. This will allow bacteria to spread onto other food.
The Danger Zone is between 5°C and 63°C
This is the temperature where bacteria reproduces fastest at.
There are various ways of killing bacteria:
Extreme temperature, no moisture, no air (tinning) or using a disinfectant to kill the bacteria.
When you cook food, you must make sure you cook it all the way through and defrost in properly or bacteria may not be killed.