Braille and its principles

Braille is a tactile writing system, created by French blind educator Louis Braille (1806—1852).

Printed braille is based on a combination of 1 to 6 raised dots within a single cell arranged in a 3 × 2 dot matrix (three dots in two columns, and are uniquely numbered here (see picture on the right).

Thus, there are a total of 64 possible combinations (including a space character and a 6-dot braille cell with all six dots raised).

Punctuation and composition signs

Since braille has only 64 combinations in the six-dot variant, it does not cover all the combinations that are commonly used in visual alphabets. The number of possible combinations is thus increased by the use of composition signs (or prefixes), which modify the value of the character that follows (see examples).

For digital work with the use of braille displays, braille is based on a cell with eight dots, which further increases the number of possible combinations to 256.

Braille systems

Some languages have multiple braille-based systems — the difference between them is the accuracy with which they reflect the visual writing system of the language (let us say accuracy of its transcription).

For example, English officially has two systems:

• Uncontracted (or Grade 1, in full spelling, consists of the letters of the alphabet, punctuation, numbers, and a few composition signs)

• Contracted (or Grade 2, consists of Uncontracted Braille plus 189 contractions and short-form words).

For more details see e. g. English Braille.

German has up to three systems:

• Basisschrift (no contractions is used for transcription; this system is very rarely used)

• Vollschrift (uses eight simple contractions for common vowel and consonant groups)

• Kurzschrift (contracted Braille — a system of abbreviations and shortening rules was created for it over time)

For more details see e. g. Das System der deutschen Blindenschrift.