The universe is a vast expanse that contains all matter, energy, planets, stars, galaxies, and even empty space. It began with the Big Bang, a massive explosion that occurred about 13.8 billion years ago, leading to the expansion of space. Over time, matter coalesced to form stars and galaxies, while gravity played a crucial role in shaping their structures. The universe operates under fundamental laws of physics, such as gravity, electromagnetism, and the strong and weak nuclear forces. These forces govern the interactions between particles and celestial bodies, influencing everything from the orbits of planets around stars to the formation of black holes in galaxies.