Creative Commons
If you can not find Public Domain media that fit your needs, you can use Creative Commons-licensed content as long as you ensure that you correctly attribute this content to its creator and otherwise meet the terms of the license under which the content is offered.
Note: Even if content is covered by a Creative Commons license, you must always make sure that your use does not violate that license and that you properly attribute the content.
Public Domain
Copyright.gov explains the public domain as follows: "A work of authorship is in the “public domain” if it is no longer under copyright protection or if it failed to meet the requirements for copyright protection. Works in the public domain may be used freely without the permission of the former copyright owner." Because such works can be used without seeking permission, they are ideal for many projects, particularly those that will extend beyond educational uses such as blogs and social media content.
Note: Even if a work that you use is in the public domain, it is advisable to provide attribution for the work or, at a minimum, keep a record of the attribution of the work, so that you or other interested parties can find it later if necessary.
Plagiarism does not only apply to writing. Plagiarism violations can occur with the illegal use of any mediums such as videos, software, digital materials, recordings, artist work, video games, etc. For this reason it is important to understand the terms Copyright and Fair use.
Copyright
According to the United States Copyright Office, copyright is a form of protection grounded in the U.S. Constitution and granted by law for original works of authorship fixed in a tangible medium of expression. Copyright is used to protect an original work of authorship, including literary, musical, artistic, and dramatic works. Although it protects these, it does not protect facts, ideas, discoveries, systems, or methods of operation.
Fair Use
The United States Copyright Office defines “fair use” as a legal doctrine that promotes freedom of expression by permitting the unlicensed use of copyright-protected works in certain circumstances.Certain types of uses—such as criticism, comment, news reporting, teaching, scholarship, and research—would be considered examples of activities that might qualify as fair use.
Copyright vs. Fair Use
These two terms can be confusing because their goals are closely related. While Fair Use allows you to utilize a work that has been protected by Copyright, it does not allow you to claim said work as your own. Fair Use only goes as far as someone being able to use it without profiting from it. On the other hand, a Copyright gives you full ownership of the work, allowing you to claim it as your own and potentially make money from the content or product.
However, Copyright does not give you any claim of ownership over something that includes your copyrighted work labeled as Fair Use. In other words, if someone were to teach a lesson that included one of your works, you could not claim ownership of that lesson.
Copyright and Fair Use act as a way to keep each other in check, with Copyright protecting your work and Fair Use allowing you to use a work that is protected by Copyright, as long as it is within the bounds of what is considered Fair Use.
Source: https://openlab.citytech.cuny.edu/whatiscopyright/fair-use/