MIDI (Musical Instrument Digital Interface) means a data structure controlling electric musical instruments.
The MIDI consists of two components: on the one hand there is the hardware, for example components like the board, MIDI cable and MIDI-jack. On the other hand there is the software, the controlling language. This language consists of standardized codes which serve the transmission of certain information, for example the pressing of a key on the keyboard.
At the beginning of the 80ies the MIDI was developed and introduced by Dave Smith in collaboration with ROLAND. The MIDI's initial idea was to control synthesizers from another keyboard to be able to replay multiple sounds with one key.
The advance of computers and the extension of their application areas gave MIDIs a new boost in the early nineties. With the help of MIDI-enabled synthesizers and computers musicians were now able to create complex or manually unplayable music pieces, since MIDI data could now be modified and corrected on computers.
In accordance to the envolving technologies MIDIs were adapted, so they soon could function as an interface for any kinds of electronic musical instruments (expander, sampler, drum computer etc.).
In addition to that the range of terminals that can be controlled through MIDIfiles also exceeds the range of classical devices. Apart from synthesizers and other digital control units, there are also MIDI-guitars, MIDI-accordions and MIDI-saxophones.
Functionality and usage
MIDIs are often mixed up with digital music files that can be played with regular devices (e.g MP3, WAV etc.). A MIDI does not "sound" on average audio systems. A MIDI does not record analog sound waves like a cassette tape. Instead it captures things being played on an instrument for example key touches, pitches and length of tones as well as volume and musical attributes (e.g vibrato). The respective receiver is not playing the MIDI, it processes the included codes. One can say that a MIDI leads a virtual orchestra.
Initially the MIDI had multiple standards, for example the Sample-Dump-Standard or the MIDI Time Code. In 1991 the General MIDI (GM) was introduced. Whereas the general MIDI standard sets specifications for hardware and protocols, the GM sets the content. This means that with the GM's launch a standard was set for the sound arrangement. With this standard from now on devices which were GM-compatible exported a piece of music equally. But equally exported does not mean, that the sound of the piece is also equal. Over the years the GM standard was expanded with adaptations from respective manufacturers like ROLAND or YAMAHA.