Why is it important to ensure that all our food items are properly cooked and not over/under cooked?

Why is it important to ensure that all our food items are properly cooked and not over/under cooked?

Answer:

Cooking food properly will help make sure that any harmful bacteria are killed . Eating food that isn't properly cooked could give you food poisoning.

And, if we overcook food, then useful bacteria die out. 

Thus, we should avoid undercooking and overcooking foods.