Copyright law is both simple and complex at the same time. It is simple because intellectual creations automatically receive legal protection. It is complex because unscrupulous people can take your work and claim it as their own anyway.
Since March of 1989, intellectual property does not require a notice of copyright to remain protected. However, it is still a good idea to include such a notice on your works. Doing so may deter someone from stealing your property and may strengthen any copyright law actions you pursue against the alleged thief.
There are two main forms of copyright notice. One protects visually perceptible works and one protects audio recordings, which are also known as phonorecords. These notices contain three basic elements.
Visually perceptible works typically use the copyright symbol ©. Alternatively, you can use the word "Copyright" or its abbreviated form, (Copr.) The second element is the year in which the work was published and the third element is the copyright holder's name. Here is an example: © 2017 John Doe.
For audio recordings, the same format is correct except that the copyright symbol has the letter P inside a circle instead of the letter C. To enhance the protection of intellectual works, all notices of copyright must be placed in a location that will be easily seen.
If you are asking about copyright law because you believe someone has stolen your intellectual property, consider consulting with a California attorney. A consultation will provide you with advice about how to take action against the person who may have stolen your work.
Source: FindLaw, "Notice of Copyright," accessed Sep. 29, 2017