The universe is everything that exists, including all matter, energy, space, and time. It is defined as the totality of existence, everything that has existed, everything that exists now, and everything that will exist. The universe includes all the physical laws that influence energy and matter, such as conservation laws, classical mechanics, and relativity. The universe is often defined as "the totality of existence", or everything that exists, everything that has existed, and everything that will exist. The universe is thought to have emerged from the Big Bang, which occurred approximately 13.787±0.020 billion years ago. The universe is still expanding, and it includes all of space and time, including planets, stars, galaxies, and all other forms of matter and energy.

The universe is made up of three types of substances: normal matter, dark matter, and dark energy. Normal matter consists of the atoms that make up stars, planets, and human beings. Dark matter is a mysterious substance that does not interact with light or other forms of electromagnetic radiation, but its presence can be inferred from its gravitational effects on visible matter. Dark energy is a hypothetical form of energy that is thought to be responsible for the accelerating expansion of the universe.

The observable universe is the region of space that humans can actually or theoretically observe with the aid of technology. It can be thought of as a bubble with Earth at its center. It is differentiated from the entirety of the universe, which is the whole cosmic system of matter and energy, including the human race. Unlike the observable universe, the universe is possibly infinite and without spatial edges.

In summary, the universe is everything that exists, including all matter, energy, space, and time. It emerged from the Big Bang and is still expanding. The universe is made up of normal matter, dark matter, and dark energy. The observable universe is the region of space that humans can observe, while the entirety of the universe is possibly infinite and without spatial edges.