The concept of an Accelerating Universe refers to the observation that the expansion of the universe is speeding up over time. This surprising discovery was made in the late 1990s when astronomers studied distant supernovae. They found that these exploding stars were farther away than expected, indicating that the universe's expansion is not just ongoing but accelerating. This acceleration is attributed to a mysterious force known as dark energy, which makes up about 68% of the universe. While scientists are still trying to understand the nature of dark energy, its existence has profound implications for the fate of the universe, suggesting it may continue to expand indefinitely.