Copyright is the right that grants the creator of any work the exclusive right to benefit (copy, distribute, being credited, deciding who else my benefit from it) from said work. That may seem obvious and not very complicated, but in times of digital distribution of music via the internet and rapid increasing popularity DJs who often work with remixes, copyright becomes very important. A copyright infringement is a violation of the copyright and means that copyright protected work (or parts of it) have been used without having permission for it. If you want to use a copyright protected song or parts of it you have two options:
1)Use it without permission. As long as you are not very successful the copyright holder most likely won’t notice. But in case you become successful using someone else’s work you will presumably get sued for copyright infringement and have to pay a fine and enlist the copyright holder in the profits you make with their song (If money is involved lawyers are never far away). For instance The Verve’s song “Bitter sweet symphony” caused a big controversy because the use of a string sample in it wasn’t negotiated clearly enough with the copyright holders (The Rolling Stones and their management) so that the management of the Rolling Stones successfully claimed 100% of the song’s profits and Jagger/Richards got credited for the song writing. The Verve still got money for live performances of the song, but any profits made trough record sales were transferred to the Rolling Stones.
2) Ask the current copyright holders for permission to use their work. In that case you will either pay one-time a certain amount of money for the right to use the song (or parts of it). This will most likely happen when you are not very successful and well known already. Or the copyright holders claim a certain percentage of the profits you make with their song.
What is important to know about the copyright in relation to remixing?
A remix is a piece of work that has been changed from the original. Remix is a very broad term, because anything form an almost completely new song to an only slightly adapted or modified version classifies as a remix. It is important to know that the copyright has two sides, the master side and the publishing side. The publishing side is the composition of the song whereas the master side is about the recording of the song such as the single stems. Most remixes are made of content from the master side, the publishing side and the new musical work put into them. To avoid making this process too complex most labels demand a one-time fee you have to pay to have the right to use their stems and musical content (master and publishing side). You should always have a written permission from both sides to use their work.