People make up new worlds. 
People can make up whole new worlds. 
Some worlds are far away in space. Other worlds look like our Earth. They might be from long ago.
In these worlds, things must make sense. If two characters meet, they are in the same world.
Sometimes, many writers work on one world. They all share the same ideas. It is fun to build a world together.
People can make up whole new worlds for stories. These are called fictional universes. You can find them in books or movies. You can also find them in video games. 
Some worlds are far away in space. They might be a distant galaxy. Other worlds look like our Earth. They might be a version of our past or our future.
In these worlds, things must stay the same. This is called continuity. It means the story rules do not change. If character A meets character B, they are in the same universe. If B meets character C, then A and C are in that universe too. Characters must meet in a story to count. Just being on a book cover is not enough.
Sometimes, many writers work on one world. They all share the same ideas. This can happen with many authors. One writer might make a world called Known Space. Other writers can then tell stories there too. Some worlds even let fans help add new ideas. An editor or creator keeps the main rules in place. 
Map of the Land of Oz. This is a place in a story series.
A fictional universe is a world made up for a story. It is also called an imagined or constructed universe. These worlds are built to be consistent. This means the rules stay the same throughout the story. You can find these worlds in many places. They appear in novels and comic books. You might also see them in films or television shows. Even video games use these special settings. 
These worlds can look very different from our own. Science fiction often uses a remote alien planet. It might even use a distant galaxy like in Star Wars. Fantasy stories use a different way. They might invent a new version of Earth. This could be a version of the distant past. It could also be a version of the far future. A famous example is The Lord of the Rings. 
There is a special way to check if characters belong together. This idea is called fictional continuity. In 1970, Don Markstein wrote about this in CAPA-alpha. He said characters must meet in a story to be in the same universe. If character A meets character B, they are connected. If B meets character C, then A and C are also connected. Just appearing on a book cover is not enough. They must appear together in a real story. 
Rules help keep these worlds from getting mixed up. You cannot connect characters using real people. For example, Superman and the Fantastic Four are not in the same universe. This is because Superman met John F. Kennedy. Kennedy met Neil Armstrong. Armstrong met the Fantastic Four. That does not make them part of one universe. You can use special versions of real people. Marvel Comics has a version of Hercules. DC Comics has a version of Robin Hood. 
Sometimes, many different authors work on one single universe. Each writer gets to tell their own stories there. These stories are called canonical. Larry Niven created a universe called Known Space. He allowed other authors to write about the Man-Kzin Wars. This happened over a 135-year period. Other series like Ring of Fire let fans help. An editor or creator still keeps control. They make sure the final changes fit the world. 
A fictional universe is a carefully built setting for a story. You might also hear it called an imagined universe or a constructed universe. These settings are defined by being internally consistent. This means the rules of the world stay the same throughout the narrative. Such universes are common in fantasy and science fiction. You can find them in novels, comics, films, and television shows. They also appear in many modern video games. 
Science fiction and fantasy use different methods to build these worlds. In science fiction, a universe might be a remote alien planet. It could even be an entire galaxy with no link to our real world. The Star Wars universe is a famous example of this type. Fantasy stories often take a different path. They might create a highly fictionalized version of Earth. This could be a version of Earth's distant past or its far future. The Lord of the Rings is a well-known example of a fantasy setting.
To understand how characters belong to one universe, we use the concept of fictional continuity. In 1970, comics historian Don Markstein wrote about this in a magazine called CAPA-alpha. He wanted to clarify how we define these connections. His rules explain how characters can be linked together. If character A meets character B, they are in the same universe. If character B then meets character C, then A and C are also in that same universe. This is a transitive connection that keeps the world organized.
However, there are strict limits to these connections. Characters cannot be linked through real people. For example, Superman met John F. Kennedy. Kennedy met Neil Armstrong. Armstrong met the Fantastic Four. Even though they are linked by real people, Superman and the Fantastic Four are not in the same universe. Characters also cannot be connected by characters that do not originate with a specific publisher. This prevents characters from being linked through figures like Hercules, unless they are specific versions. 
Special versions of real people can act as valid connections. For instance, DC Comics created a version of Jerry Lewis in The Adventures of Jerry Lewis. This version was different from the real person because he had a housekeeper with magical powers. This rule also applies to public-domain characters. Marvel Comics has its own version of Hercules. DC Comics has its own version of Robin Hood. These specific, fictionalized versions allow for a shared continuity. To count as a meeting, characters must appear together in a story. Simply appearing on the same front cover is not enough to link them.
Sometimes, a single fictional universe is shared by many different prose authors. In these cases, the stories written by each author are given approximately equal canonical status. Canonical status means the stories are accepted as part of the official history of that world. Larry Niven created a universe known as Known Space. He allowed other authors to write stories about the Man-Kzin Wars. This period of shared writing covered approximately 135 years. This allows a universe to grow much larger than one person could write alone.
Other series use a different approach to growth. The Ring of Fire series actively seeks canonical stimulus from its fans. This means fans can suggest or provide ideas for the world. However, the creator and the editor still control the process. They use a formalized system to gate and control any changes. This ensures the universe remains consistent even when many people contribute to it. Through these rules, authors can build massive, complex worlds that feel real to the reader.
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