"세자" refers to the title of a crown prince in the context of the Korean monarchy. This position is typically held by the eldest son of the reigning king, who is designated as the heir to the throne. The role of the 세자 is crucial, as he is expected to learn the responsibilities of leadership and governance in preparation for becoming king. In historical Korea, the 세자 often received special education and training to prepare for his future role. He was involved in state affairs and ceremonies, representing the royal family. The title is significant in understanding the lineage and succession of the 조선 왕조 (Joseon Dynasty) and its royal family.