A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.

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For questions that require answers based on hard science, not magic or pseudo-science, but do not require scientific citations. Contrast with the hard-science and reality-check tags. Do not use this t…
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realistic in a given context. Answers should say yes or no, with supporting info. Compare this with the science-based and hard-science tags. This tag should never be the onl…
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For questions about living things. Does not exclude aliens, but additional information is usually necessary (consider using "xenobiology" instead).
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For questions dealing with how sentient beings interact with each other in a community.
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For questions that have to do with magic, as opposed to science/technology. Remember to explain any limits.
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For questions about the creation, use, and application of all types of technology.
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For questions about any large astronomical bodies classified as planets, and their effects on their systems.
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For questions regarding the viability of a life-form design. These questions should focus on biologically plausible creatures.
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For questions relating to worlds with a setting of common science-fiction.
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For questions related to the effects of certain circumstances, conditions, or locality changes on war. Related tags: [civil-war], [nuclear-war], [cold-war]
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For questions regarding the physics relevant to fictitious worlds. General physics may be off-topic.
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For questions about the long-term change of a specific species, type of creature, or trait, usually through the process of natural selection and reproduction. Consider also [creature-design].
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For questions related to outer space, stellar systems, stars and other astronomical phenomena.
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For questions about existing weapons or designing new ones.
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For questions about humans as we know them or slightly changed, their physiology, psychology, politics, society and goals.
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For questions about a different and uncharacteristic species or object that has come to the world from another world. NOT for questions about extraterrestrials in their native environment.
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For questions regarding wealth, trade, or financial concepts.
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For questions about an environment or aspects of it such as geographical, atmospheric or climate.
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to mark questions related to creating plausible alien biologies that may be close to or far removed from Earthly biology but within the realms of hard science.
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For questions about the process of traveling through space, including in orbit around a planet or moon. Consider also [spaceships]. See also the tag information (click "info") for more details on when…
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For questions about the medieval era (500-1500AD o.e.) as a whole.
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Requires answers backed up by equations, empirical evidence, scientific papers, other citations, etc. Contrast with: science-based and reality-check tags. This tag should never be the only tag on a qu…
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For questions involving implemented theory or technology for travelling through space. Consider also [space-travel]. See also the tag information (click "info") for more details on when this tag appli…
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For questions that ask what might have happened if history had taken a different path.
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For questions regarding planets similar to Earth in most respects. This tag should be used when describing a planet that follows the rules of Earth with exceptions outlined in the question. Usually q…
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For questions dealing with the political body with authority over a nation or world and its people.
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For questions dealing with the customary and artistic characteristics of a society.
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For questions about governance of the people, including methods, effects, and interactions with the people.
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For questions dealing with events taking place after a catastrophic event.
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For questions about specific changes in the characteristics of the weather in a location. You should also consider the tags [weather] and [seasons].
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For questions about the progress of a society's technological state.
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For questions about the characteristics and effects of natural features on a world.
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For questions about the universal accelerative force between all objects.
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For questions pertaining to natural satellites, such as our own Moon.
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For questions about animal life in general.
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For questions about the gases which surround a planet or some other celestial body.