What does this symbol, a letter C in the middle of a circle, mean?

? is the copyright mark.

The copyright mark traditionally used in China is the word "Copyright". The copyright mark must usually be accompanied by explanatory text regarding the copyright status of the work. For example, the Universal Copyright Convention stipulates that the copyright mark consists of the copyright symbol, which is the first letter of the English word "copyright" plus a circle.

The copyright mark traditionally used in China is the word "Copyright". The copyright mark must usually be accompanied by explanatory text regarding the copyright status of the work. For example, the Universal Copyright Convention stipulates that the copyright mark consists of the copyright symbol, which is the first letter of the English word "copyright" plus a circle.

All copies of the work must bear a mark in an appropriate location, which mark includes (1) the word copyright or its abbreviation or symbol; (2) the year of first publication; and the name of the actual copyright owner.

The requirement for such a mark as a condition of copyright protection for published works is accepted by the Universal Copyright Convention, the Rome Convention and the Phonograph Convention, but under the Universal Copyright Convention the first item of the mark should always be the copyright symbol. See the "Copyright Page" section.