Alternate Timelines/Parallel Universes, etc...

For those of you novice comic book readers (or not so novice!) looking for a brush up on all the weird ways in which the Marvel writers (and DC,and... ah, heck they all do this once in a while) get away with making characters do things that are not 'normal' and/or you ever had a small shudder when you heard the term "Parallel Universe" because you thought, "Now, how does that differ from Alternate Timeline?" --- here is a rundown of the differences...Merci, Amy:

1) "OUR" WORLD: the mainstream Marvel universe (pretty self-explanatory)

2) ALTERNATE TIMELINES: These take place in our world, but involve something that "went wrong" that causes some problematic, horrific future. Major examples of alternate timelines are Days of Future Past, Age of Apocalypse, and recently Here Comes Tomorrow. In order to prevent the terrible future, someone must go back to prevent the specific incident that started the chain reaction.

- Days of Future Past: Caused when Senator Kelly was assassinated. Prevented when adult Kitty went back in time, inhabited her younger self, and stopped the assassination.

- Age of Apocalypse: Caused when Legion killed Xavier. Prevented when Bishop goes back in time to kill Legion.

- Here Comes Tomorrow: Caused when Scott left the school, leaving the students in others' hands after Jean's death. Prevented when Phoenix rewound time and telepathically "nudged" Scott to stay at the school.

Because alternate timelines cause new scenarios and relationships, certain people can be born that may not exist in our world. Examples are Rachel Summers from DFP and Nate Grey from AOA.

Obviously, alternate timelines can be affected by people from our world (see above ways that the timelines were "prevented." )

3) PARALLEL WORLDS: These are NOT our world, but rather a parallel dimension with parallel people and places, but probably unique circumstances. This is a pretty common theme in a lot of sci-fi books and TV shows. (We all have a parallel in another dimension, etc.)

Examples of this are the Mutant X parallel world, as well as the numerous parallel worlds that the Exiles visit in each issue.

A key difference between parallel worlds and alternate timelines is that nothing "went wrong" on the parallel world to make it different from ours. It simply IS different from ours in certain ways, simply by nature.

Obviously, parallel worlds can be affected by people from our world. "Our" Havok was sucked into the parallel Mutant X world and the Exiles move from dimension to dimension.

4) RE-TELLINGS: Similar to parallel world, but main difference is that a re-telling exists INDEPENDENTLY from all others. It re-tells the origins and stories of the characters, but basically keeps their personalities the same.
Technically speaking, the X-men movies and cartoons are re-tellings.
In the movies, Wolvie and Rogue are rescued by Storm and Cyke, and that's how they end up at the mansion. In the X-Men Evolution cartoon, Storm and Wolvie are adult teachers in charge of teenage Scott and Jean. Obviously, this is not how it is on "our" world, but these are re-tellings of how it all came about. In the comics, the Ultimate X-men issues are re-tellings. (For instance, Wolvie first comes to the mansion because he was sent by Magneto to kill Charles) Again, that didn't "really" happen, but that is how this particular series is presenting the character's origin.

A good way to tell the difference between a re-telling and alt timelines and/or parallel worlds is that a re-telling can NOT be affected by people from our world. It exists completely separately and independently from the mainstream Marvel universe. Polaris from "our" world is not going to be suddenly sucked into the Ultimate X-men issues any more than she would suddenly be sucked into an X-men cartoon. If she does appear in a cartoon or the movie or an issue of Ultimate X-men, she will have her own introduction. She would not just be whisked out of our world, and dropped into the re-tellings. Again, re-tellings can NOT be affected by people from our world, but alternate timelines and parallel worlds CAN and ARE affected by people from our world.

5) WHAT IF'S: These are hypothetical scenarios. They basically tell us "if this had happened, then this is what would have come after." It should be noted that some What If issues do actually take place in parallel worlds rather than just as a hypothetical situation. The issue itself will tell you whether it's hypothetical or something that occurs in a parallel world.