Public domain software

Public-domain software is software that has been placed in the public domain: in other words, there is absolutely no ownership such as copyright, trademark, or patent. Software in the public domain can be modified, distributed, or sold even without any attribution by anyone; this is unlike the common case of software under exclusive copyright, where software licenses grant limited usage rights.In the 1950s to the 1990s software culture, as original academic phenomena, 'public-domain' (usually abbreviated to 'PD') software was popular. This kind of freely distributed and shared 'free software' combined the nowadays differentiated software classes of freeware, shareware and free and open-source software and was created in academia, and by hobbyists and hackers. As software was often written in an interpreted language such as BASIC, the source code was needed and therefore distributed to run the software. PD software was also shared and distributed as printed source code (type-in program) in computer magazines (like Creative Computing, SoftSide, Compute!, Byte etc.) and books, like the bestseller BASIC Computer Games. Early on, closed-source software was uncommon until the mid-1970s to the 1980s.Before the Berne Convention Implementation Act of 1988 (and the earlier Copyright Act of 1976, which went into effect in 1978) works could be easily given into the public domain by just releasing it without an explicit copyright notice and no Copyright registration. After the 1988 implementation act, all works were by default copyright-protected and needed to be actively given into public domain by a waiver statement.See also Category:Public-domain software with source code, Category:Public-domain software