LilyPond is a free music engraving program developed by the LilyPond development team. It enables users to produce and print sheet music in a traditional layout. The result is reminiscent of the time when musical scores were engraved by hand. Since it is a text-based application, users are supposed to write and edit documents that have musical notes instead of creating an arrangement using a mouse. Although the program currently does not have a graphical interface, the process of creating a score is simple. The music input comes in text format, which is then interpreted by LilyPond and subjected to a series of processes, the end of which is the conversion to graphical formats like PDF and PNG.
LilyPond also has the ability to import MusicXML files and generate MIDI files. The program follows a WYSIWYM model, which requires the user to write content in a structured manner. The developers have resolved various typographical issues; for instance, the duration of each note is reflected exactly by the way they are positioned. In addition, readability has improved by reducing the length of the ledger lines. Spacing of serial notes are done with respect to stem directions, and the music font design is modified based on the size of the staff.