Dark energy is a mysterious force that makes up about 68% of the universe. It is believed to be responsible for the accelerated expansion of the universe, counteracting the gravitational pull of matter. Scientists are still trying to understand its nature and properties, as it does not emit light or energy, making it invisible and difficult to detect. The concept of dark energy emerged from observations of distant supernovae, which revealed that the universe is expanding at an increasing rate. This surprising discovery has led to various theories, including the cosmological constant proposed by Albert Einstein, and has significant implications for the fate of the universe.