Selling

Copyright is a form of Intellectual Property, and like any form of property it can be bought, sold, transferred, inherited, and so on. If you do decide to sell or transfer your copyright there would need to be a written, signed contract stating a transfer has taken place. This is known as an assignment.

You should note that when certain copyright material is created the creator, even if they sell their copyright the creator will still have moral rights. This provides the author/creator with the right to be identified as the author and to object to any derogatory treatment of the work.