may involve shifting the tempo or changing the general mood of the set. Track choices are also due, in part, to where the DJ wishes to take his or her audience. In this way, the resulting mixset is brought about through a symbiotic relationship between audience and DJ. Studio DJs have the luxury of spending more time on their mix, which often leads to productions that could never be realized in real-time. Traditional DJ mixing with vinyl required the DJ to sync the tempo of the tracks and modify each track's volume and equalisation to create a smooth blend. DJs can use a mixer's crossfader to switch between tracks or use the volume control for each source with the crossfader permanently positioned in the middle. Mixing is usually done through the use of headphones and a monitor speaker or foldback as basic aids. At this basic level, the DJ is required to develop a specific auditory skill where each track's tempo has to be distinguished while listening to more than one piece of music. The use of compact discs and players such as the CDJ brought technological advances for the DJ performing a mix including a readout of the bpm and a visual representation of the beat. Modern computer technology has allowed automatic beatmatching and led to debate regarding its use, which is sometimes described as cheating. DJ software provides automatic beatmatching and key detection which simplifies harmonic mixing. Legality To be released commercially, DJ mixes often need many copyright clearances and licenses. The vast majority of DJ mixes throughout the years have only avoided legal action because the copyright holders generally do not choose to take legal action against the DJ for the unauthorized use of their material. Distribution During the late 1990s and early 2000s, DJs would often distribute their recorded mixes on CD-Rs or as digital audio files via websites or podcasts for promotional purposes. Many popular DJs would release their mixes commercially on a compact disc. With declining CD usage, it has become more common for DJs to release their mix recordings through websites specifically set up for the purpose. Some of these sites, such as Mixcloud, and formerly Mixcrate, allowed for legal streaming of DJ mix recordings through established revenue deals with record publishing companies. When DJ sets are distributed directly via the Internet, they are generally presented as a single unbroken audio file; cue