You arent allowed to copy an entire album or book and sell it basically.
Why because you are not the publisher, they have standards and the author needs to be paid.
You can copy some of it, they call it fair use. if you are USING it for something, not selling it. eg referencing, it, using it for study, quoting from it, performing an excerpt, using it as inspiration, sharing etc, then that is 'fair use'.
If you are still not sure what I mean by Fair use, google fair use and copyright law and wiki can probably explain it .
Libraries do pay a fee that allows them to share books and yhe authors do get compensated for loss of royalties that happens when people dont buy their books because they are freely available to be borrowed. Radio also pays a fee so that they can play songs on the radio free for people to listen to.
when you are the original author of something thats you own work...you have the copyright and can let others copy it only with your permission. If you are not bothered, about being original, then you just share the work under creative commons and it doesnt matter who copies it.