What is bankai?

Bankai is a highly advanced and powerful form that Shinigami in the anime and manga series Bleach can achieve. By releasing their zanpakuto's true form and power, a Shinigami can access a Bankai, which significantly enhances their combat abilities and grants them new techniques and powers. Bankai is considered the ultimate form of a zanpakuto, and only the most skilled and powerful Shinigami are able to achieve it. To activate Bankai, the Shinigami must speak the release command for their zanpakuto, followed by the word "Bankai."