Plagiarism:

Copying someone else's work then publishing it as your own.

Fair use:

A legal concept that allows the reproduction of copyrighted material for certain purposes without obtaining permission and without paying anything.

Piracy:

Illegal copying, distribution, or use of software.

Copyright License: It is an authorization by the copyright owner to enable another party to engage in behavior that would otherwise be the exclusive right of the copyright owner, but without transferring title in those rights. This permission can be granted for the copyright itself, for the physical media containing the copyrighted work, or for both the copyright and the physical media.