piano music and sheet music

In the late 20th and into the 21st century, significant interest has developed in representing sheet music in a computer-readable format (see music notation software), as well as downloadable files. Music OCR, software to "read" scanned sheet music so that the results can be manipulated, has been available since 1991.

In 1998, virtual sheet music evolved further into what was to be termed digital sheet music, which for the first time allowed publishers to make copyright sheet music available for purchase online. Unlike their hard copy counterparts, these files allowed for manipulation such as instrument changes, transposition and MIDI (Musical Instrument Digital Interface) playback. The popularity of this instant delivery system among musicians appears to be acting as a catalyst of new growth for the industry well into the foreseeable future. 

An early computer notation program available for home computers was Music Construction Set, developed in 1984 and released for several different platforms. Introducing concepts largely unknown to the home user of the time, it allowed manipulation of notes and symbols with a pointing device such as a mouse; the user would "grab" a note or symbol from a palette and "drop" it onto the staff in the correct location. The program allowed playback of the produced music through various early sound cards, and could print the musical score on a graphics printer. 

Many software products for modern digital audio workstation and score writers for general personal computers support generation of sheet music from MIDI files, by a performer playing the notes on a MIDI-equipped keyboard or other MIDI controller or by manual entry using a mouse or other computer device.