GNU LilyPond is a computer program for music engraving. One of LilyPonds major goals is to produce scores that are engraved with traditional layout rules, reflecting the era when scores were engraved by hand. It uses a simple text notation for music input, which LilyPond interprets and processes in a series of stages. In the final stage, music notation is output to PDF (via PostScript) or other graphical formats, such as SVG or PNG. LilyPond also has the facility to generate MIDI files that correspond to the music notation output.
LilyPond is a text-based application, so it does not contain its own graphical user interface to assist with score creation. It does, however, have a flexible input language that strives to be simple, easing the learning curve for new users. LilyPond adheres to the WYSIWYM paradigm; the workflow for typesetting music notation with LilyPond is similar to that of preparing documents with LaTeX.
LilyPonds primary goal is to produce output comparable to professionally-engraved scores instead of output that looks mechanical and computer-generated
It produces very elegant looking sheet music