Braille music is a Braille code that allows music to be notated using Braille cells so music can be read by visually impaired musicians. The Braille music system was originally developed by Louis Braille.
Braille music uses the same six-position Braille cell as literary braille. However braille music assigns a separate meaning to each braille symbol or group of symbols different from literary braille and has its own syntax and abbreviations.
Almost anything that can be written in print music notation can be written in braille music notation. However, braille music notation is an independent and well-developed system with its own conventions.
The world's largest collection of braille music is located at the National Library for the Blind in Stockport, UK.
Braille music is in general neither easier nor more difficult to learn than print music. Visually impaired musicians gain the same benefits upon learning to read braille music as sighted musicians who learn to read print music. Visually impaired musicians can begin learning braille music about the time they have reasonable competence reading literary Braille. 
Braille music for beginners, like print music for beginners, is quite simple. Music teachers with no previous knowledge of braille music can easily learn the rudiments of braille music notation and keep a step or two ahead of the student who is learning braille music. Some common print method books are available in braille so a sighted teacher can use a print version and the visually impaired student braille version or the other way around.
Much commonly used music has been transcribed into braille. In the US, this is available from the National Library Service (NLS) of the Library of Congress (free for qualified individuals) and through other sources. Most countries have a national library similar to the NLS.
However, many visually impaired musicians require a good deal of music that has never before been transcribed. In the United States, Canada, United Kingdom, and many other countries, there is a network of braille music transcribers who can transcribe such music.
Another option is to use a computer-music system. Such systems typically allow a user to enter music into a computerized music notation program. The software then automatically converts the print notation into braille. One such software program is called Goodfeel. The visually impaired individual can enter music notation within the Lime program, which has been scripted so the process of music entry is accessible. Then this file can be imported into Goodfeel which converts the music into a Braille file that can be exported to a Braille embosser or read on a portable Braille display.
Some of the most common braille music symbols and combinations are summarized in the chart below:
As the "Notes" section of the music braille chart above indicates, a single symbol shows both the pitch and rhythmic length of a note. For instance, dots 1,4,5 indicate an eighth note (or 128th note) C. Every rhythm symbol in braille music does double duty—8th notes and 128th notes use the same symbols, as do quarter notes and 64th notes, half notes and 32nd notes, and whole notes and 16th notes. Beginners first learn the most common rhythmic value (8th, quarter, half, and whole notes). For advanced users there is never rhythmic ambiguity because the context, including time signature and bar lines, makes the intended rhythmic value clear. For instance, in a measure of 4/4 time that includes only the symbol with dots 1,3,4 (whole or 16th rest), context says the symbol must indicate a whole rest.
An octave mark is included before a note symbol to specify the octave of the note. For instance, the 4th Octave is the octave starting with middle C and going up to the B above middle C. Octaves are only specified when needed. For instance, a melody proceeding upward from the first octave can, if moving by step, proceed to the second, third, and fourth octaves without requiring additional octave signs. The rule is that, in the absence of an octave mark specifying otherwise, notes move by a unison, 2nd, or 3rd rather than a 6th, 7th, or octave. For instance, the following moves upward continuously, ending in octave 5:
The rule for 4ths and 5ths is different, however: in the absence of an octave sign specifying otherwise, a melodic leap of a 4th or 5th will stay within the same octave as the previous note. For instance, the following always stays within Octave 2:
Because of the use of octave marks, clef symbols are not required in braille music. On occasion, clef symbols (bass clef, treble clef, or other) will be indicated so the visually impaired musician will be aware of every detail of the print score.
Musical indications like "dim", "cresc", or "rit" are inserted inline with the note and rhythm notation and, to differentiate them from note, octave, and other musical signs, always preceded by the "word sign" (dots 3,4,5).
Slurs may be indicated by a slur sign between two notes or bracket slur surrounding a group of notes to be slurred.
Musical signs such as staccato or tenuto are generally placed before the note or chord they affect. The musical signs shown on the chart are shown modifying a quarter note C (dots 1,4,5,6).
"Music hyphen" is used to indicate that a measure will be continued on the following line (this happens somewhat more often in braille music than in print music).
A "word apostrophe" indicates that the word will be continued on the following line.
Braille music tends to be rather bulky. Because of this, a system of repetition symbols—much more extensive than that in print music—is employed to reduce page turns, size of scores, and expense of printing.
In addition, braille music often includes instructions such as "repeat measure 2 here" or "repeat measures 5-7 here". Such indications are in addition to the commonly used repeat marks and first and second endings.
Unlike print music notation, braille music is a linear format. Therefore, certain conventions must be used to indicate contrapuntal lines and chords, situations where more than one note is played simultaneously within a staff.
Independent contrapuntal lines within a staff are indicated via whole- or part-measure in-accords. The first of the contrapuntal lines is given, then the second, enclosed by the in-accord symbols. The in-accord symbols indicate that the two lines are to be played simultaneously.
Homophonic chordal sections are written using interval notation. For instance, the notation "quarter-note-C, 3rd, 5th" would indicate playing a C along with the notes a 3rd and 5th higher than C, making a chord C-E-G a quarter note in length. Reading the interval notation is somewhat complicated by the fact that some staves use bottom-up notation (the bottom note of each chord is specified and intervals are read upwards from the given note) and some use top-down notation (the top note of each chord is specified and intervals are read downwards from the given note). The modern convention is to specify the main note (either the bass line or melody line) and let the intervals go up or down from there as appropriate. For instance, in most piano music the left hand specifies the bottom note and intervals go bottom-up while the right hand specifies the top note and intervals go top-down. Many older scores have all staves reading bottom-up or all reading top-down. Most scores have a note indicating the direction of the interval notation. However, in some older scores the direction must be established from the context. By convention, in-accords are given in the same direction as the interval notation. Thus, examining the in-accords is one way to establish whether the interval notation on a particular staff is bottom-up or top-down.
Printed music is often written on several different staves. For instance, piano music is typically written on two different staves combined into the grand staff: one for treble clef and one for bass clef, while choral music often has four different staves (one each for soprano, alto, tenor, and bass). The notes in different staves that play simultaneously are aligned vertically. Because of the linear nature of braille music and the fact that the blind musician can typically read only one staff at a time, multiple staves are handled in several ways depending on the complexity of the music and other considerations. Bar over bar format is most similar to print music. Simple piano music in bar over bar format is quite similar to print music, with right-hand notation on the top line and left-hand notation on the bottom line. Some degree of vertical alignment between the right and left hands is maintained. Other ways of dealing with multiple-staff music are line over line format, section by section format, paragraph style, and bar by bar format. As a rule these formats take up less space on the page but require more of the musician in working out how to fit the staves together. For instance, in a piano score notated in section by section format, the right-hand part may be written out for the first 8 measures, followed by the left-hand part. No attempt is made to align the parts. The same procedure is followed for measures 9-16, and so on, section by section, throughout the score. The blind musician learns and memorizes one section right hand alone, then left hand alone, then works out the hands together by memory and referencing various spots in the braille score to work out how the sections fit together. A note from the transcriber often clarifies the format used. However, with many older and more complex scores the format must be determined by examination of the music and context.
Over the years and in the many different countries, a variety of minor differences in braille music practice have arisen. Some countries have preferred a different standard for interval or staff notation or used different codes for various less common musical notations. An international effort to standardize the braille music code culminated in the updates summarized in Braille Music Code 1997 and detailed in the New International Manual of Braille Music Notation (1997). However, users should be aware that they will continue to encounter divergences when ordering scores from printing houses and libraries because these are often older and come from various countries.