Dreaming is an ability that has been granted to only humans and what marks our difference from other life forms. Dreams are necessary because it is through dreams that we achieve greatness, ambition, innovation. But of course, a person who spends his time only dreaming about things but never takes any steps to bring them to reality, are futile dreams. Such dreams are waste and not ones that are used to achieve things.

No i don't think that it is wasteful because if we don't dream then how can we know our ambition so to do more in life one should dream 

By dreaming about a goal, you are visualzing it within your mind. Dream is the subtle form of the reality what you expect. If you can convert your dreams into thoughts and you feed them in your subconscious mind with  emotions and feelings, they will become your beliefs. If your beliefs are stronger, your subconscious mind and inner powers will act on them and make them into reality in due course, so that finally you get what you dream. 

Ask the Booking clerk for a ticket. He will question you, where do you want to go ?. It implies that for any journey destination is important. Akin to this, for life's journey also a destination is important. Dreams are necessary to define your destination . Your Dreams will act as a Road map on the journey of life. Never stop dreaming to reach your destination that is your cherished Goals.

@rambabu

The example of a ticket booking clerk sounds so simple but so very effective in putting forth your opinion. Yes, if there is no destination then life will be just like a ship without a rudder.   

And this destination is very essential which can be achieved only through dreaming.

Dreams help us achieve the goals of our life because dreaming encourages us to live a better standard. Therefore, dreams are necessary because dreams help us build up the character. Dreaming is very fruitful.

They say dreams define destination. This enables you to set an aim and chase your cherished goals.

After all, our missile-man Dr. APJ Abdul Kalam said-

" Dream Dream dream...

Dreams transform thoughts and thoughts result in action."

So, there is no provision of genuine dreams being waste of time however, dreams should be genuine and strong enough to let us not sleep. Yes, dreams during our sleeping hours are just the imagination of our mind.

After all, our missile-man Dr. APJ Abdul Kalam said-

" Dream Dream dream...

Dreams transform thoughts and thoughts result in action."

So, there is no provision of genuine dreams being waste of time however, dreams should be genuine and strong enough to let us not sleep. Yes, dreams during our sleeping hours are just the imagination of our mind.