Braille (breɪl , bʁɑj) is a tactile writing system used by people who are visually impaired, including people who are blind, deafblind or who have low vision. It can be read either on embossed paper or by using refreshable braille displays that connect to computers and smartphone devices. Braille can be written using a slate and stylus, a braille writer, an electronic braille notetaker or with the use of a computer connected to a braille embosser.
Braille is named after its creator, Louis Braille, a Frenchman who lost his sight as a result of a childhood accident. In 1824, at the age of fifteen, he developed the braille code based on the French alphabet as an improvement on night writing. He published his system, which subsequently included musical notation, in 1829. The second revision, published in 1837, was the first binary form of writing developed in the modern era.
Braille characters are formed using a combination of six raised dots arranged in a 3 × 2 matrix, called the braille cell. The number and arrangement of these dots distinguishes one character from another. Since the various braille alphabets originated as transcription codes for printed writing, the mappings (sets of character designations) vary from language to language, and even within one; in English Braille there are 3 levels of braille: uncontracted braille - a letter-by-letter transcription used for basic literacy; contracted braille - an addition of abbreviations and contractions used as a space-saving mechanism; and grade 3 - various non-standardized personal stenography that is less commonly used.
In addition to braille text (letters, punctuation, contractions), it is also possible to create embossed illustrations and graphs, with the lines either solid or made of series of dots, arrows, and bullets that are larger than braille dots. A full braille cell includes six raised dots arranged in two columns, each column having three dots. The dot positions are identified by numbers from one to six. There are 64 possible combinations, including no dots at all for a word space.