Illéa is a fictional nation in the popular book series "The Selection" by Kiera Cass. It is a monarchy that emerged after the United States underwent significant changes, leading to a new social structure and class system. The country is divided into different castes, which determine a person's social status and occupation. The royal family of Illéa plays a central role in the story, particularly through the character of Princess America Singer. The narrative explores themes of love, class struggle, and the challenges of royal life, as America navigates the complexities of participating in a competition to win the heart of Prince Maxon.