I'm not even really sure what to title the thread. But basically, I'm wondering about what constitutes plagiarism and copyright infringement. For example, is anyone who uses elves (of similar type as Tolkein) actually plagiarizing? What if someone uses magic based on an ancient language? What if someone creates a world where mages are hated and feared? Can concepts, such as (but not limited to) the ones above be plagiarism, or does a persn have to copy more than one aspect (such as a world with both elves and hated mages), or is a person pretty much safe unless they actually steal exact phrasing? Is there a certain point where something is used so mainstream that it basically becomes public domain? (Such as nature-loving elves.) What determines what's open to public use and what belongs to an author? I've just always wondered about this, but I haven't been able to find examples or anything online. Explanations for what constitutes plagiarism are always very vague.