This category lists articles that have a separate companion article to provide a general non-technical introduction to laypersons who may not be able to understand or wish to get into the intricacies and technicalities necessary in the main article. While the articles in this category provide a formal encyclopaedic treatment of their topic, the companion articles offer a more introductory approach. Add the template ((see introduction)) to include articles in this category. Please avoid manual inclusion, use the template!

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