A work for hire is an exception to the general rule that the person who creates a work is the author of that work. According to copyright law, if a work is "made for hire", the employer, and not the employee, is considered the author. The employer may be a firm, an organization, or an individual.
The works are usually signed by the employee. For example, Microsoft hired many programmers to develop the Windows operating system. The system software is credited to Microsoft Corporation. So are newspapers' editorials. These articles are not signed by anyone and is also credited to the paper. They are written to express the paper's opinion.
Sometimes, an employer may let the employee sign the work. For example, other than the editorial, most articles in a newspaper are signed by the reporters even though they are hired by the paper. If the employer hires a famous person to create something, the employer may also want to let the true author be credited.
Most works for hire are created by nobody. You don't usually see the technical writer's name printed on a 10-page-long coffee pot manual. In this case, the employer has all the rights to reuse or modify the texts written by its employees. However, if Acme Corporation hires David Hockney to design its out-board motor box, there is no reason not to let people know it. In that case, the moral rights may belong to Mr. Hockney but Acme keeps the economic rights. If the contract allows it, Acme may print David Hockney's signature on the box so the credit goes to Mr. Hockney.
Similar concepts can be seen in many countries' copyright laws, here is "Works Made for Hire" defined by the Copyright Act of the United States:
Works Made for Hire. -- In the case of a work made for hire, the employer or other person for whom the work was prepared is considered the author for purposes of this title, and, unless the parties have expressly agreed otherwise in a written instrument signed by them, owns all of the rights comprised in the copyright. 17 U.S.C. sec 201(b)
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