Fair Use
Limited use of copyrighted material — not a blanket licence
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Fair use is a defence in US copyright law: for criticism, teaching, news and research, limited use of copyrighted material may not require permission each time. Courts weigh four factors: purpose and character, nature of the work, amount used, and effect on the market.
It is not a blanket licence, and not "credit the source and you are fine": every use is judged on its own, and fair use is a US doctrine — other countries have different rules. The usual mistake is to think "non-commercial equals fair use" — non-commercial is only one factor, not a shield. When in doubt, clearing rights is safer than betting on a defence.
Read deeper → copyright
Sources
- 合理使用的四要素与法域差异，参通行版权教材；本文为通识说明，不构成法律意见
Used for fact-checking only; all prose is original.