The universe is the totality of space, time, matter, and energy. It began around 13.8 billion years ago with the Big Bang and has been expanding ever since. It contains billions of galaxies, each holding stars, planets, nebulae, and black holes. Our home, Earth, lies in the Milky Way Galaxy. The observable universe stretches about 46.5 billion light-years in radius, though the actual universe may be infinite. It is governed by natural laws such as gravity and electromagnetism. Mysterious elements like dark matter and dark energy dominate it. The universe remains vast, dynamic, and full of unanswered questions.