Copyright protects everything that someone creates, writes, or publishes online, and prevents someone else from stealing their hard work and claiming it as their own. This can be an essay, a photo, a drawing, or test answers.
Fair use happens when somethings is able to be used without it being counted as copying, but it requires you to still sight your sources. This is so that we are able to write research papers without getting the permission of every single source that we want to use. This does not mean I could copy a whole book, but it does allow for me to take out parts of it to teach on.
Stealing is never acceptable in my classroom, and this includes stealing something from online. Always give me your own ideas, and if you are using someone else's thoughts for an assignment, rewrite it in your own words and provide me a source.