Braille is a technique for enabling blind and visually-impaired people to read and write.
Refined in the late 1800's by Louis Braille for blind people, it was originally developed
by a French army captain to enable officers to read battle commands without the aid of
candle light hence revealing your position.
Each braille character or "cell" is made up of 6 dot positions, arranged in a
rectangle comprising 2 columns of 3 dots each. A dot may be raised at any of the 6
positions, or any combination. Counting the space, in which no dots are raised, there are
64 such combinations. For reference purposes, a particular combination may be described by
naming the positions where dots are raised; the positions being universally numbered 1
through 3 from top to bottom on the left and 4 through 6 from top to bottom on the right.
For example, dots 1-3-4 would describe a cell with three dots raised, at the top and
bottom in the left column and on top of the right column. Because the 64 distinct
characters are never enough to cover all possible print signs and their variations, it is
necessary to use multi-character sequences for some purposes. Often this is accomplished
by using certain characters as "prefixes" or "indicators" that affect
the meaning of subsequent cells. For example, a dot 6 before a letter indicates that the
letter is a capital, whereas otherwise it is understood to be lower case. For another
example, dots 3-4-5-6, called the "numeric indicator", causes certain following
letters (a through j) to be reinterpreted as digits.
Dot height, cell size and cell spacing are always uniform, and so many significant
characteristics of the text, such as italics used for emphasis, must be handled by such
indicators in Braille. An exception to that formatting, such as the centering of main
headings, is commonly used in Braille in much the same way and for most of the same
purposes as in print.
Separate braille codes may be used for notation systems other than natural languages such
as music, mathematics and computer programming.
Partly because of the size that Braille pages occupy, and partly to improve the speed of
writing and reading, the literary braille codes for English and many other languages
employ "contractions" that substitute shorter sequences for the full spelling of
commonly-occurring letter groups. For example, "the" is usually just one
character in Braille. When contractions are used, the Braille is usually called
"grade 2" in contrast to "grade 1" transcriptions where all words are
spelled out letter-for-letter.
What does it look like?
Below is the layout of a Braille cell. It consists of two columns and three rows, with
each dot read as "dot 1, dot 2, etc".
Each letter of the alphabet is listed below. Numbers are written by using the
"a" as"1", "b" as "2", etc up to "j" as
"0". Special symbols preceding a Braille cell indicate whether a number follows.