Copyright is often black-and-white, but sometimes there are nuances. Here's an example of that gray area:
Mashup artist Girl Talk creates music by taking small sections of existing songs and layering them to create a new work. 372 songs from other artists come together to form the music on the album All Day (2010).
Since Girl Talk arrived on the music scene, legal experts have debated whether or not this style of music violates the copyright of the original creators who created the songs that Girl Talk samples.