From the United States Copyright Office Web Site (https://copyright.gov/what-is-copyright/):
Copyright is a type of intellectual property that protects original works of authorship as soon as an author fixes the work in a tangible form of expression. In copyright law, there are a lot of different types of works, including paintings, photographs, illustrations, musical compositions, sound recordings, computer programs, books, poems, blog posts, movies, architectural works, plays, and so much more!
Copyright Is Originality and Fixation
Original Works
Works are original when they are independently created by a human author and have a minimal degree of creativity. Independent creation simply means that you create it yourself, without copying. The Supreme Court has said that, to be creative, a work must have a “spark” and “modicum” of creativity. There are some things, however, that are not creative, like: titles, names, short phrases, and slogans; familiar symbols or designs; mere variations of typographic ornamentation, lettering, or coloring; and mere listings of ingredients or contents. And always keep in mind that copyright protects expression, and never ideas, procedures, methods, systems, processes, concepts, principles, or discoveries.
Fixed Works
A work is fixed when it is captured (either by or under the authority of an author) in a sufficiently permanent medium such that the work can be perceived, reproduced, or communicated for more than a short time. For example, a work is fixed when you write it down or record it.
A form of protection provided by the laws of the United States for "original works of authorship", including literary, dramatic, musical, architectural, cartographic, choreographic, pantomimic, pictorial, graphic, sculptural, and audiovisual creations. "Copyright" literally means the right to copy but has come to mean that body of exclusive rights granted by law to copyright owners for protection of their work. Copyright protection does not extend to any idea, procedure, process, system, title, principle, or discovery. Similarly, names, titles, short phrases, slogans, familiar symbols, mere variations of typographic ornamentation, lettering, coloring, and listings of contents or ingredients are not subject to copyright.
https://www.copyright.gov/help/faq/definitions.html
In general, for works created on or after January 1, 1978, the term of copyright is the life of the author plus seventy years after the author’s death. If the work is a joint work with multiple authors, the term lasts for seventy years after the last surviving author’s death. For works made for hire and anonymous or pseudonymous works, the duration of copyright is 95 years from publication or 120 years from creation, whichever is shorter. For works created before January 1, 1978, that were not published or registered as of that date, the term of copyright is generally the same as for works created on or after January 1, 1978. The law, however, provides that in no case would the term have expired before December 31, 2002, and if the work was published on or before that date, the term will not expire before December 31, 2047. For works created before January 1, 1978, that were published or registered before that date, the initial term of copyright was twenty-eight years from the date of publication with notice or from the date of registration. At the end of the initial term, the copyright could be renewed for another sixty-seven years for a total term of protection of up to ninety-five years. To extend copyright into the renewal term, two registrations had to be made before the original term expired: one for the original term and the other for the renewal term. This requirement was eliminated on June 26, 1992, and renewal term registration is now optional. https://www.copyright.gov/circs/circ01.pdf
Copyright is a form of legal protection that provides authors of original creative works with limited control over the reproduction and distribution of their work. It gives copyright holders a set of exclusive rights to
These rights are subject to exceptions and limitations, such as "fair use," which allow limited uses of works without the permission of the copyright holder.
Copyright protects "original works of authorship." To be protected by copyright, a work must be original and recorded. It cannot be copied or expressed without being recorded.
Types of works protected by copyright include:
What is not protected by copyright?
What does this mean for you as an author?
You do not need to register your work to have copyright over it, once you create a work in tangible form you have the rights to it. You have a right to control:
However, you should note that adding a copyright notice, creative commons license (thought this allows for copying of work with attribution), or registering your work with the U.S. Copyright Office is a smart move to make.
Effectively managing your rights as a copyright owner can help you to maximize the impact of your research and scholarship.
Depending upon when a work was created, it is subject to different requirements regarding copyright notice and registration, as well as different copyright terms.
For example, before 1978 U.S. law required that works be published with a notice of copyright to receive protection. Failure to comply with this requirement would result in the work being in the public domain.
Copyright Term and the Public Domain, a guide to copyright duration created by Peter Hirtle at Cornell University, is a comprehensive and useful resource for researching a work's copyright status. You can also use the Copyright Slider from the American Library Association for quick reference.
As a general rule, works registered or published in the U.S. before 1924 are in the public domain.