The universe is everything that exists, including all matter, energy, planets, stars, galaxies, and even the empty space between them. It is vast and ever-expanding, containing billions of galaxies, each with millions or even billions of stars. Our own galaxy, the Milky Way, is just one of many in this incredible cosmic expanse. Scientists study the universe to understand its origins and how it works. The Big Bang theory suggests that the universe began as a tiny point and has been expanding ever since. By observing distant galaxies and cosmic events, researchers learn more about the universe's history and its future.