The copyright symbol
The copyright symbol or logo, C-in-a-circle or ©, is one of the most famous symbols in the world. Its original meaning was to indicate a copyright had been obtained for the work on which it was displayed. Today copyright protection is automatic, so no registration or inclusion of a copyright symbol or notice is necessary anymore. Still, the copyright symbol serves as a useful indicator that the copyright holder cares about his copyright.
The copyright symbol originated in US copyright law. From the first US copyright law until the 1979 law, a work was required to have a proper copyright notice. Without a valid notice, the work was not protected by copyright. One of the elements of the notice was the word "Copyright". This word could be abbreviated as "copr." or the c-in-a-circle symbol (©) could be used instead.
The copyright symbol is the symbol ©, a c in a circle. How to produce this symbol depends on the character set used when writing a text. In the ISO Latin 1 (ISO 8859-1) character set used on the World-Wide Web, this character is item number 169.
In communication media like e-mail or ASCII text, it is sometimes not possible to type or include this symbol. Some people substitute "(C)" or "(c)" since that closely resembles the copyright symbol. The laws that deal with copyright notices do not allow any deviations from the c-in-a-circle. It is thus questionable whether a court in such a jurisdiction would consider a "(c)" or "(C)" a valid alternative for a copyright symbol.
On the other hand, there are very few practical circumstances under which the distinction between © and "(c)" or "(C)" is important.
People who want to use the absolutely correct form under all circumstances should not use the © symbol but instead the word "copyright" or the official abbreviation "copr."