Hello Kundan,
Firstly I want to tell you that we here at Careers360 will definitely help you out through all means possible by us and solve all related queries, no matter how many they may be.
This is an interesting question and I would like to elaborate this.

The inside margins closest to the spine of a book or the blank space between two facing pages in the center of a newsletter or magazine is known as the gutter. The gutter space includes any extra space allowance needed to accommodate the binding of books, booklets, pamphlets, newspapers, and magazines.
This space has to be treated importantly as it may be taken as waste and that wouldnt really add to profits.

I hope this helps!

All the best!