Public domain software

1. The term public domain in general refers to the free use of the work or object without any restrictions. This may be because of the lack of a copyright or because the work is no longer owned.
2. When referring to software, public domain refers to software that can be freely distributed and used, either because the company has released it to be public domain or because the company is no longer in business. Public domain software may or may not carry a copyright.

Also see: Copyright, Freeware, Open source software, Software