Radon is a dangerous gas. It is colorless and odorless and is always being emitted from our planet-don't worry, it's not enough to harm you.
Copyright for published works in the USA has been according to a federal copyright statute, since the first U.S. copyright statute in the year 1790. Before the Copyright Act of 1976 became effective on 1 Jan 1978, unpublished works were. protected by state law, known as common-law copyright.
Know what isn't protected. Copyright law generally does not protect the underlying ideas of a creative work, and it does not protect facts. For example, copyright doesn't prevent you from expressing in your own words ideas and facts found in a book or journal you read.