The three-body world and the three-body problem were two different concepts. The three-body problem was an important concept in the science fiction series," The Three-Body Problem." It referred to a universe made up of three-body civilizations. The Three-body Civilization was a highly developed alien civilization. Its civilization structure, social system, values, and other aspects were very different from humans. Therefore, there were huge differences between them. This was also one of the main topics of this series of novels. The Three-Body World referred to the universe depicted in the novel. It was the space where the Three-Body Civilization was located, and it was also an important concept in the novel. In the novel, the Three-Body World was a mysterious and unknown place filled with all kinds of wonderful creatures and technology. It was also one of the main backgrounds for the plot and the development of the characters in the novel. Therefore, the three-body world and the three-body problem were two different concepts. The former referred to a specific universe, while the latter was a concept in the novel.