The Chūnin Exams are a bi-annual, multi-stage competition in the Naruto universe that allow low-ranking ninja (Genin) to be promoted to intermediate ninja (Chūnin). They test intelligence, survival skills, and combat prowess while serving as political showcases of military strength for allied villages.
The first stage of the Chūnin Exams (famously featured during the Chūnin Exams Arc in Naruto) is a written examination designed to test a genin's information-gathering skills, stress management, and resolve rather than their academic knowledge.
In the Naruto series, the 2nd stage of the Chunin Exams is a grueling, multi-day survival test designed to push genin to their absolute limits. Proctored by Anko Mitarashi, the most famous version of this exam takes place in the deadly 44th Training Zone, aptly named the Forest of Death. Teams must fight each other to secure two specific scroll types before reaching a central tower.
The 3rd stage of the Chūnin Exams in the Naruto universe is the final, climactic phase. It functions as a public, one-on-one martial arts tournament where Genin showcase their combat prowess, tactical intelligence, and leadership skills to various Kage, Feudal Lords, and potential clients.
Technically, no one won the tournament. The final round in the original series was cancelled midway due to the Sand and Sound ninja invasion of Konoha. However, Shikamaru Nara was the only participant officially promoted to Chunin because he displayed the tactical intelligence expected of a leader.