FOR THOSE WHO DO NOT KNOW WHAT THE HUNGER GAMES IS, LOOK HERE :
The "Hunger Games" plot revolves around a dystopian society where punishment for a previous rebellion has resulted in a televised event. One boy and one girl between the ages of 12 and 18 from each district (there are 12 total) are selected at random and forced to participate in the Hunger Games, where “tributes” must fight to the death until only one is left standing.
This summary is not written by me. It is written by the person who wrote this article : http://hungergamesmovie.org/2065/cnn-examines-what-is-the-hunger-games/
EDIT : In The Hunger Games, The Reaping is what is used to determine who is going to go into The Hunger Games. There are two containers, one for the boys, and one for the girls. They both have slips of paper in them with the names of everyone ages 12-18 in the District. Someone pulls out a slip of paper, reads the name, and whoever's name it is, goes into the Games.
If you see in the book something saying "the Games", it is referring to The Hunger Games.