Public domain may refer to any of the following:
The term public domain in general refers to the free use of the work or object without any restrictions. A work may be in the public domain because it is not copyrighted, its Copyright has expired, or its license specifies allows its use by the public.
When referring to software, public domain is software that can be freely distributed and used. Public domain software may or may not carry a Copyright.
Business terms, Freeware, Open source software, Software, Software terms