The words ‘public domain’ means creative works that for one reason or another are not protected by copyright law and are ordinarily free for all to use. The status might have been expired and not been renewed. A computer program is in the public domain if it is not covered by any kind of copyright.
Most of the material on the internet is not in the public domain but much is. Works in the public domain are considered to be any materials that any citizen can freely access and retrieve in repositories of public records, copy, distribute or otherwise utilize without permission or license from anyone.
A large and growing number of public domain materials are available on the internet. For example, Project Gutenberg is crating digitizes versions of great literary works and making them available for downloading on the internet.
Huge numbers of databases are on the internet. Many of these are in the public domain because their selection and arrangement are not sufficiently creative to be protected by copyright.
However, licenses and other means are frequently used to protect such databases.
A work can enter to public domain for many reasons. The most common reason is that the copyright expires. Other types of works receive no copyright protection.
The notion of public domain stems from the French ‘domaine public’ which made its way into international and national law though the Berne Convection.
The meaning of public domain on the internet