The three characteristics of existence in Buddhism, also known as the Three Marks of Existence, refer to the fundamental qualities that define all phenomena: impermanence (anicca), suffering (dukkha), and non-self (anatta). These characteristics illustrate the nature of reality and are essential for understanding the Buddhist path toward enlightenment, as they emphasize the transient nature of life, the inherent dissatisfaction present in existence, and the absence of a permanent self.