In the United States, copyright is an AUTOMATIC protection of an original work. Copyright does NOT need to be applied for, but can be registered if the creator so wishes.
Furthermore, you do not need to use the copyright symbol on your work in order for it to be protected. However, registering copyright does provide benefits, including legal protection. For more information on registering copyright, please see the Copyright Registration Portal.
In order to be original, a work must be created independently. A work must also be "fixed" in order to be protected under copyright, which means it must be preserved in some from through a tangible medium.
The following are a few examples of mediums which can be protected under copyright:
(Copyright Basics, 2018)
©2018, Regents of the University of Michigan. Copyright Basics: Copyrightability. (n.d.). Retrieved June 17, 2019, from https://guides.lib.umich.edu/copyrightbasics/copyrightability
In the United States, copyright protects only “original works of authorship fixed in any tangible medium of expression.” To be eligible for copyright protection, a work must be:
©2018, Regents of the University of Michigan. Copyright Basics: Copyrightability. (n.d.). Retrieved June 17, 2019, from https://guides.lib.umich.edu/copyrightbasics/copyrightability