The Public Domain is the state of belonging or being available to the public as a whole, and therefore not subject to copyright. Works in the public domain are those whose exclusive intellectual property rights have expired, have been forfeited, or are inapplicable. Visit Wikipedia to learn more about the Public Domain.
Creative Commons also provides tools that work in the “all rights granted” space of the public domain. Their CC0 tool allows licensors to waive all rights and place a work in the public domain, and the Public Domain Mark allows any web user to “mark” a work as being in the public domain. Visit the below link to learn more about the Creative Commone CC0 license.