What is formula of humanity in ethics by Kant

Kant's formula of humanity in ethics is the principle that individuals should always treat humanity, whether in themselves or in others, as an end in itself and never merely as a means to an end. This means that individuals should always respect the inherent worth and dignity of human beings, and should never use them as a tool to achieve their own goals or objectives. The formula of humanity is one of the key principles of Kant's ethical philosophy, and is often seen as a cornerstone of modern human rights and dignity.