A lot of content found online -- including images, graphics, full text articles, among others -- have licenses.
Licenses tell users how they're allowed to use the licensed content. Sometimes the creator (artist or author) has control over the license and sometimes a third party publisher has control. Some licenses are very restrictive, and some allow for easy sharing (like Creative Commons). Licenses are the first line of defense. If there is no license in place, we fall back on copyright law.
Content found online may look like it's "free to use," but probably has a license attached. Many licenses allow for free individual use, but not for sharing with large groups, or may charge a fee for sharing with groups. It's important to understand the license before including an image in material that will be shared.
Fair Use is a legal principle that provides certain limitations on the exclusive right of copyright owners. Fair use allows use of materials for purposes of criticism, news reporting, teaching, and research, without the need for permission from or payment to the copyright holder. Fair Use is a defense, not permission.
Not all education use falls under Fair Use.
Use the PANE criteria to determine whether something falls under fair use:
If you can make a strong case for all 4 aspects, you may be able to claim fair use.
Fair Use is a defense, not permission.
The public domain is the space where no intellectual property rights exist. Works in the public domain may be used without any restrictions whatsoever.
What's in the public domain?
Examples of works in the public domain:
Works not in a "tangible form of expression," such as improvisational speeches or performances that have not been written or recorded
Ideas, regardless of the form in which it is described, explained, illustrated, or embodied in such work
Facts, or works consisting entirely of information that is commonly known and containing no original authorship, such as calendars, height and weight charts, tape measures and rulers, etc.
U.S. Government Works
Lots of other things, like recipes, fashion designs, domain names, genetic code, titles, names, short phrases, slogans, familiar symbols, procedures, methods, and systems
Open Access refers to content made freely available online without restrictions to access (without payment or institutional subscription). That doesn't mean anyone can re-use open access content however they choose. Licenses and copyright law still apply.
Creative Commons provides free, easy-to-use copyright licenses to make a simple and standardized way to give the public permission to share and use your creative work–on conditions of your choice.
For two reasons: