Destiny Under the Stars

What is a world? A planet is a world, the solar system is a world, a galaxy is a world, but what about the entire universe? Some people say the number of Ganges in the world, others say that the world is divided into large thousand worlds, middle thousand worlds, and small thousand worlds, all with a number of three thousand (three thousand is a general term, not only three thousand, it should mean infinite). So how do we understand the world?