A-theory, also known as presentism, is a philosophical concept about time that suggests only the present moment is real. According to A-theorists, the past has already happened and the future has yet to occur, meaning that only what we experience right now truly exists. This view emphasizes the importance of the present and how it shapes our understanding of reality. In contrast to B-theory, which posits that all points in time are equally real, A-theory focuses on the dynamic nature of time. Proponents of A-theory argue that our experiences and perceptions are tied to the present, making it the most significant aspect of our existence. This perspective influences various fields, including philosophy, physics, and psychology.