Why are electric wires covered with plastic?

It's actually pretty easy to guess. I remember in my science class I was asked this question in every damn exam. I have perfected the explanation on why are electric wires covered with plastic. 

The simple answer is that plastic is a bad conductor of electricity. 

Okay let us understand in detail why do electrical wires have a plastic covering.

Imagine you hold a live wire in your hand which is not covered in plastic. What will happen? You will get a shock or there are chances of electrocution. To avoid all of this, a plastic covering is placed on electric wires. This covering prevents the current to flow outside the system.

Plastic is non-reactive material made by polymerization of small organic molecules having higher molecular weight. Another reason for using plastic to cover electric wires is that they are flexible and durable. And of course, it is reasonably priced.

I hope this resolves your query why are electric wires covered with plastic.