It was required then under US copyright law that a proper copyright notice should be placed in any copyrightable work to indicate that copyright is claimed on said work; without a valid notice, the work was not protected by copyright. This symbol is considered an abbreviation of the word “copyright.”
The abbreviation “copr.” could also be used instead of the symbol.
Filipinos use the symbol although our own copyright law does not require this symbol as an element of copyright notice.
Today, copyright protection is automatic for any copyrightable work. Once a work is created, copyright automatically attaches to it. Registration is not necessary but is important for evidentiary purposes. Some people still use the copyright symbol to indicate that their work is protected.
