Multitrack recording or tracking has been around since the mid 1950s. It allows for different components of music to be recorded on different tracks. So, for example, drums might be on one track, guitar on another, vocals on a third and so on. The recording is done by line inputs into the mixer, either from amplifiers, or from the instruments themselves. Although old 4- and 8-track analog tape recorders are still available, most recording is now done digitally with recording software.
A mixing console is the first thing most people think of when they hear "recording studio." Also called an audio mixer, sound board or mixer, the mixing console is the long board with sliding controls in a traditional recording studio. The mixer is used to combine or mix the different tracks of an audio recording. It can change the level, dynamics or timbre of the audio signals. Both digital and analog mixers are widely available. Although digital mixers are inexpensive, many recording engineers still prefer analog boards for ease of use. In most cases analog mixing boards can be connected to digital recording equipment and software.
A variety of other items may be added to the studio. Some of the most common of these are intended to supplement, augment or replace live instruments. MIDI devices and synthesizers can be used for piano and keyboard sounds but can also be used to artificially create other sounds and instruments for recording. Tone generators, samplers and rhythm machines create procession and other sounds to supplement live instruments or re-create sounds on demand.
A variety of software packages allow for the recording and mixing of music. Some software packages even come with built-in synthesizers, rhythm machines and more. The leaders for professional recording are AVID's Pro Tools and Adobe Audition, but these are only a few of dozens of possibilities. Apple's Garage Band allows for multi-track recording, mixing and has built-in synthesizers, yet it is inexpensive and even comes pre-installed on many new Macs. Audacity by Sound Forge allows for multi-track recording and mixing, has a variety of available plug ins and is free for Windows, Mac, Linux and Unix.