The national book week is a 10 day 'week', which aims at promoting literature and books to society.
Each year, the week revolves around a different theme. If you buy a book during this week, you will get the bookweek gift for free. This is always a book written by a Dutch writer, but not necessarily about the theme. However, there is also a special essay written for this week, which is always about the theme of the week. The night before the start of the week, an opening Gala takes place in the 'Stadsschouwburg' in Amsterdam.
It is also possible to use the bookweek gift as your train ticket. On the Sunday of the week, one can travel in all Dutch national trains for free, by showing the book.