An acknowledgment in law is a declaration by the person who has signed a document that their signature is a voluntary act made before a duly authorized person, such as a notary public.
In copyright law, fair use permits the quotation or reproduction of a small portion of copyrighted material (with proper acknowledgment) without the permission of the copyright holder. The permissible amount varies based on several factors, with the central idea being that the use should not significantly impact the market for the original work.
