A parallel universe, also known as a parallel dimension or alternate reality, is a hypothetical self-contained reality that exists alongside our own. In this concept, every decision or event could create a branching universe, leading to different outcomes and experiences. This idea is often explored in science fiction and theoretical physics, suggesting that there may be countless versions of reality. The concept of parallel universes is linked to theories in quantum mechanics, particularly the Many-Worlds Interpretation. This interpretation posits that all possible outcomes of quantum measurements actually occur, each in its own separate universe. While intriguing, the existence of parallel universes remains a topic of debate among scientists and philosophers.