Authors and composers own the rights to their compositions. This is what is commonly referred to as "copyright" protection. Essentially their work or composition is protected from the use or exploitation by others for many years. The general rule of thumb is if a publication's origin occurred prior to 1923 that that work is considered in the public domain. For more detailed information on compositions being in the public domain, please refer to the "U.S. Copyright Office-Copyright Basics", a U.S. Government publication. The site provides the following summary:

• Works registered before 1 January 1923 had copyright protection for 75 years and that protection has expired, placing the original works of authorship in the public domain.
• Works registered after 1922 and before 1 January 1978 enjoy a 75 year copyright protection.
• Works created after 1977 enjoy the longest copyright protection, which is the lifetime of the longest surviving plus another 70 years.

Also be aware that one does not need to file for copyright protection in order to enjoy its privilege. However, in order to prosecute another for copyright infringement one must first register their copyright.

"Copyright protection subsists from the time the work is created in fixed form. The copyright in the work of authorship immediately becomes the property of the author who created the work. Only the author or those deriving their rights through the author can rightfully claim copyright."