Sheet Music
Music, like any other art form, has a language of its own. For literature, the language is words. For Art, it is paint. For music, it is sheets of paper with 'bars', 'stems', 'clefs', 'key signatures', 'time signatures', and dozens of other little details that distinguish George Gershwin's "Concerto in F" from "Mary Had A Little Lamb". For as long as there has been music, there has necessarily been some form of sheet music so that the melodies can be replayed by musicians other than the original composer or composers. Sheet music exists for any kind of music from Symphonies to Operas to Broadway show tunes, encompassing every different style and instrument.
The sheet music is made up of staffs or staves. The stave is five horizontal lines, generally extending the width of the page. In a full score of an Opera, each staff represents a musical instrument or voice. In a Piano score, designed specifically for that instrument, the "treble" and "bass" symbols on the left of the page indicate the notes that the right hand (treble) and left hand (bass) play. Also at the left of most any page of sheet music is the time signature, such as 4/4, 3/4, 2/4, etc., indicating how the music is counted. Key signatures, represented by sharps (#) and flats (b's) indicate the key of the music, and then there are the notes themselves, separated by rests. Notes are written differently, depending on how long the composer wants them held. For example, in 4/4 time, a "whole note", which looks like a hollow oval, is meant to be held for four beats. A 'quarter note', which is black and unconnected with a single stem, would be held for one.
All these elements, including many others, work together to form either an individual song, or the "score", as it is called, to a larger work, such as a musical. When copyrighting an individual song, interestingly enough, not all the music has to be written out. A "lead sheet" will suffice for copyright, meaning that only the melody, lyrics, and harmony are required on the sheet music. After the key signature and time signature are given, and the melody written out, chord symbols written on top of each stave represent the harmonies. It takes some effort to learn how the different chord symbols (C7, dm7, F#maj, etc) relate to their respective notes on the piano. Once learned, however, this saves time and effort when submitting a song for protection.
There are arrangements for virtually every song and for every instrument. When starting to learn any instrument, it is a good idea to choose from a very simple arrangement of a very simple song, with few notes. After that, one can increase the difficulty level with more complicated songs. It takes time and perseverance to learn any musical piece, but considering the wealth of wonderful music in the world, the effort is well worth it.