Copyright means something is protected from usage against the owner’s approval of use, this could be a quote, research, and other materials. Something doesn’t need to have the copyright tag to be protected. This is something many don’t realize. Copyright Infringement can be expensive, and one could have no idea the material used was protected because of the earlier assumption. This is something common on the internet.
The four tests of fair use involve whether the materials will be used non-commercially, for example in a lesson at a school. Also, if the work copied was published or not as this can determine how protected the material is. Another thing to look at is how much is being copied, if only a bit is used then, most likely, it is alright to use; the more you use the less it is allowed to be copied. And finally you have look if the usage of the material is harming the market use for the owner; if the usage financially hurting the owner. The type of media/material used matters because not all types of materials era protected the same and this is something very important to know or the consequences can hit you fast and hard.