Copyright Overview
Copyright and Cultural Institutions by Peter Hirtle, Emily Hudson, & Andrew T. Kenyon
A digital textbook available freely covering many concepts in copyright from its history, fair use, library exceptions, public domain, and more. Contains great charts, flowcharts, and tips to help users answer questions like is this work are available in the public domain or how to determine whether this use is considered fair use, can the library reproduce this copyrighted material for archiving purposes and many more.

Copyright for Educators & Librarians
An online 5 week copyright course geared towards educators and librarians that aims at educating them on an overview of copyright covering topics like fair use, exceptions for teachers and librarians, and owning rights.

Association of Research Libraries’ Copyright Timeline of History
A detailed timeline of copyright from its origins to 2014 featuring summaries and rulings on court cases and implemented laws.

Center for History and New Media – US Copyright Office
A brief history of the U.S. Copyright Office and its functions. Also included is a brief timeline of notable dates relating to U.S. copyright.

The Surprising History of Copyright & The Promise of a Post-Copyright World

Copyright Law of the United States
A complete full-text version of the December 2011 U.S. Copyright Law.

Copyright in General
A brief explanation from the U.S. Copyright Office on copyright basics from what is it to what does it protect.

Is It Still in Copyright?
Copyright Status Flowchart for Work Created Between 1923-1977
A flowchart to determine whether a work created between January 1, 1923 and December 31, 1977 is either a public domain work or still in-copyright.

Image in the public domain found via Columbia Copyright Office.