Music mixing is taking the different parts of a recorded piece of music and mixing them into a whole piece of music. Specifically, it is the art and science of combining multitrack recordings into a single final track, whether mono, stereo, or surround sound. A music mixer typically starts by adjusting the relative levels of each track, setting and even automating them so that the balance of the mix is optimized at all times. The process involves intense use of hardware and/or software gear such as compressors, reverbs, delays, equalizers, and other tools to create the desired sound. Many apply these effects to both single tracks and groups of tracks “bussed” together and treated as a single. Mixers control the “depth” of sound using volume, the “width” using the stereo field, and the “height” using frequencies. A mixing engineer typically uses a digital audio workstation (DAW) or a hardware mixing console.