What is the difference between Paper back, soft cover and hard cover?

Any clue????
I have no idea :P

Paper back is a book having flexible finding.

Soft cover - designating any book bound in flexible cover as plastic or imitation of leather.

Hard cover - the cover of book produced from a flexible material, usually cloth or paper supported by right boards

Paperback means the cover of the book is made of a thicker paper whereas hardback is made from a hardboard and is bound with a cloth fabric on top of the hardboard.

thank you kalyani for detailed explaination. Actually this question asked by my friend as she need to write articles on it. but we didnt get proper information in google