There are four major exceptions to the copyright law that are commonly used by educators: face-to-face instruction, virtual instruction, library use, and fair use. Exceptions allow for using a work without permission from the copyright holder and potential fees.
If the use does not qualify under face-to-face instruction or virtual instruction, then fair use is generally utilized because it is broader and more flexible. Or the copyrighted work may be released under an open license like Creative Commons, which grant you permission to use the work under certain circumstances.
It is the decision of the individual using the work which exception is applicable. It should be a conscious decision not a decision by default. If no exceptions are applicable, then permission should be requested from the copyright holder. Printing services can obtain copyright clearances for members of the university community. Also see Getting permission: how to license & clear copyrighted materials online & off (ebook) for tips on obtaining permission to use copyrighted works.
A work is in the public domain if its term of copyright protection is over, or if it never met the requirements for copyright protection in the first place. Works in the public domain can be used for any purpose without permission or licensing.
As defined in copyright law, face-to-face instruction takes place when the instructor and students of a nonprofit institution are in a place dedicated to instruction and the teaching and learning take place at the same time (such as a classroom). In this setting, all performances and displays of a work are allowed.
Virtual instruction happens when a course is taught solely online or when parts of a usual face-to-face course are taught using a system like Scholar. Virtual instruction often entails digitizing class materials so students can access them online. This access is authorized under 17 U.S. Code § 110, also known as the 2002 TEACH (Technology Education and Copyright Harmonization) Act.
Fair use allows you to use copyrighted works without permission for a limited and transformative purpose, such as commentary, criticism, news reporting, teaching, scholarship, research, or parody. Fair use exception to copyright is not as defined as other exceptions, such as classroom or library uses. Only court cases provide definitive exceptions.
17 U.S. Code § 107 spells out four factors to determine if a use is fair. You must weight each of these factors, no single factor is decisive. The ALA's fair use analysis tool will assist you with weighing the factors and will email you your choices so you'll have a record.
Copyright law has explicit exceptions for libraries copying works. Libraries can copy works for preservation or security purposes, and in limited cases, to replace missing or damaged works. In general, these exceptions are not applicable to educational or research uses. Other exceptions do have such applications.
If copyrighted material has been posted under one of the many open licenses (Creative Commons is one popular example), you don't need permission from the copyright owner to make use of the materials, you just need to follow the restrictions of the license. These restrictions frequently include attribution (properly citing the material), and can include restrictions on commercial use or how the material can be adapted or changed.