This symbol takes the shape of a capital c letter inside the circle, and it means that a specific company or a person own a particular product. This product can't be used without the owner's consent.
The sign was introduced in the United States through the copyright act in 1909. In the beginning, it was limited to certain types of products like graphic and sculpture, and then it was extended in 1954. Since the symbol was not available on typewriters and computers, it was common to use (C) to give the same function as the current copyright symbol.