What is the most important part in hunger games book 1?

In The Hunger Games book 1, the most important part is the selection of the tributes for the 74th Hunger Games. This event is the starting point of the story, and it sets the stage for the rest of the book. During the selection, Katniss Everdeen volunteers as tribute in place of her younger sister, Primrose, and Peeta Mellark is selected as the male tribute from District 12. This event forces Katniss and Peeta to face the dangers and challenges of the Hunger Games, and it also sets up the conflict between the Capitol and the districts. The selection is also significant because it shows the power and control that the Capitol has over the districts.