The universe is the vast and unlimited space where everything like matter, energy and time exist. So, it consists of billions of starts, nebula, planets, satellites, meteorites, comets, dust particles etc.
Basically, The Universe is everything we can touch, feel, sense, measure and detect. It includes living things, planets, stars, galaxies, dust clouds, light, and even time. Before the birth of the Universe, time, space and matter did not exist. The Universe contains billions of galaxies, each containing million or billions of starts and galaxies in largely empty. The Universe is incredibly huge and it would take a modern jet fighter more than a million years to reach the nearest star to the sun. The Universe is always expanding and scientists believe it began in the a big bang which took place nearly 14 billion years ago.