Ghost: do you believe on that if not then why you affraid of that!

It is the common fear to all childen from their relatives in childhood that the ghost will come and take you out. Children used to do all the things that he/she did not follow before. They always try to not take food or becoming naughty in meal time in that time if you say the ghost is coming they will be very much affraid which will make them follow all those. Now, it came to our mind what made us to be affraid of ghost? is there anythig really in the world.
It has been said in many books that there is no existence of ghost in the world... but there are are angle to come.
The final question came to my mind that what if the ghost woud exist in the world?
May be people would never become affraid of that because children only fear which is does not exist in the world.....