Copyright refers to laws created by a country grants creators of original works exclusive rights over how a work is used to distributed for a certain period of time. These rights usually cover attribution, reproduction, distribution, public performance, and derivative works, hence "All Rights Reserved."
Copyright laws can differ by country, as there is no universal copyright law.
The original purpose of copyright laws in the United States was to encourage creative and artistic endeavors by granting creators rights that would allow them to profit commercially off their creative works for a set amount of time, after which the works copyright would expire along with the creators rights to that work. Currently in the U.S. all "fixed works" (as in, not just an idea) are automatically copyrighted, but filing with the U.S. Copyright Office, which is under the Library of Congress, will make it easier to defend one's copyright in court.
Though copyright terms in the U.S. have changed over the years, a general rule of thumb for current copyright terms is the authors life plus 70 years (after their death).
Creative Commons (CC)
Founded in 2001, Creative Commons allows creators to apply more flexible copyright licenses to their works that allow for reuse, adaptation, and remixing. This was a direct response to the ease of sharing information on the internet, where some creators felt a traditional "all rights reserved" copyright was too restrictive.
Creative Commons Licenses
These are the four basic building blocks of the CC license. They can be combined to provide various levels of access depending on the creators wishes:
This license lets others distribute, remix, tweak, and build upon your work, even commercially, as long as they credit you for the original creation. This is the most accommodating of licenses offered. Recommended for maximum dissemination and use of licensed materials.
This license lets others remix, tweak, and build upon your work non-commercially, and although their new works must also acknowledge you and be non-commercial,
No Derivative Works:
This license allows for redistribution, commercial and non-commercial, as long as it is passed along unchanged and in whole, with credit to you
This license lets others remix, tweak, and build upon your work even for commercial purposes, as long as they credit you and license their new creations under the identical terms. This is the license used by Wikipedia, and is recommended for materials that would benefit from incorporating content from Wikipedia and similarly licensed projects.
Public domain generally refers to works with expired copyright, though some creators choose to publish original work free of any copyright restrictions.
When a work's copyright term expires, there are no longer legal restrictions placed on how it can be used. In the United States, any works published before 1923 are in the public domain. Additionally some types of government documents and other sources are automatically in the public domain.
The general rule of thumb for copyright terms in the U.S. is the life of the author plus 70 years, though there are numerous exceptions.
A tool to designate the creator relinquishes any inherent rights to original work; the CC0 license is a way to clarify the creators intent no matter the copyright laws of different locations and jurisdictions.