What is “Public Domain”?
Almost any work created before 1924 is considered to be in the public domain, as is any work created by a United States Government Agency. No copyright is involved.
However, a new edition of a public domain work could be published with an introduction, commentary, illustrations or other additions that WOULD be covered by copyright. For example, the works of Jane Austen are not under copyright, but if an editor brought out an annotated, illustrated edition, that edition would be under copyright.
Works created after 1925
Work created after 1925, with the exception of publications by U. S. government agencies, may be covered by copyright. For information about copyright for these works, visit the Copyright Information Center at Cornell University.