A more thorough explanation:

A copyright application is a written request made by the creator of a work to obtain copyright protection. This request is filed with the U.S. Copyright Office and must be accompanied by a filing fee and either a deposit copy of the work or approved identifying material.

For example, if a musician creates a new song, they may file a copyright application with the U.S. Copyright Office to protect their work from being used without their permission. The application would include a fee and a copy of the song or other identifying material.

It is important to note that failing to meet the deposit requirement of the Copyright Act of 1976 can result in the loss of copyright protection. For instance, in the case of Coles v. Wonder, the registrant did not meet the deposit requirement and lost their copyright protection.