Copyright refers to a body of exclusive rights granted by law to copyright owners for the protection of their original works of authorship. By U.S. law, original works are protected by copyright automatically at the time of their creation. A copyright symbol or notice is not required.
This protection lasts the lifetime of the creator plus 70 years, or 120 years from the date of creation. The creator of a work can sell or license their copyright protection to a publisher. In general, works created prior to 1923 are in the public domain, meaning they can be used by the public for free.