Most creative or intellectual works are eligible for copyright protection. However, the nature of the work and the time and place of publication can help determine if something is protected by copyright or whether it is in the public domain.
For works in the public domain, there are no restrictions or required permissions on publishing, editing, redistributing, or otherwise using the material in any context. Attribution of original authorship is still recommended. Use the US Copyright Terms chart to determine if a work is in the public domain.
Anything written, drawn, filmed, recorded, or artistically crafted can be protected by copyright. A work is not required to contain a copyright notice to receive protection. Copyright laws grant the creator of a work the exclusive rights to copy, distribute, perform, display, or adapt their work. When you wish to use someone else's work that may be copyrighted there are several questions you must ask:
Creative Commons License Chart