An illustrator may spend months making a field guide that another publisher could reproduce quickly. Copyright gives rights over specified uses of that work, making permission something the rightsholder can grant, withhold, or license for payment.
The crucial boundary is that copyright protects expression rather than the underlying ideas or methods. The illustrations and wording of a guide are different from the facts it describes. Writing about a new machine does not by itself secure the kind of protection associated with patents.
Imagine the illustrator permitting a school to translate the guide. The agreement can specify what may be reproduced and adapted. With open licensing, permissions can instead be offered in advance to an open-ended public, reducing repeated negotiations.
Rights can also organize sharing
Copyleft uses copyright-based conditions to preserve specified freedoms when covered work is redistributed. Sharing under such terms is an exercise of rights, not necessarily their abandonment.
The same rights can make reuse difficult when the holder is hard to find or permissions are fragmented. Scope, duration, exceptions, and ownership rules vary across legal systems. Having rights also does not ensure an income: readers must still want the work, or another arrangement such as patronage must support its creation. The social mechanism joins creative work to decisions about access, adaptation, and payment.