licenses are a way for a copyright holder to grant some rights of reproduction to others. One common way this is used is on Flickr and UTube where people put up their images and immediately grant a creative commons license so that others can use the images without asking for permission as long as they give credit. There are different types of Creative Commons licenses, some of them also allow "transforming" the work, taking it and making changes.
is the protective legal framework enacted by national governments to protect the creative product of their citizens, often for a set number of years. Traditionally academic authors have had to sign away their copyright to journal articles in the agreements they sign with journal publishers. Book publishers often just ask for specific rights.