What is Braille?
D. Indumathi, The Institute of Mathematical Sciences, Chennai

Braille is not a different language. It is a code. It is a system of reading and writing a specific language without the use of sight. Braille enables people with blindness and visual impairments to read through touch. 
We celebrate World Braille Day every year on January 4th because it’s Louis Braille’s birthday. He’s the inventor of braille. Louis was born in 1809 in France and became blind after a childhood accident. But he quickly mastered his new way of living. When Louis was only 15 years old, he created a reading and writing system based on Charles Barbier’s night writing system. We know Louis’ system today as braille. Adjusted over time, braille is now easier to read and used worldwide!
Though Louis Braille created the tactile reading and writing system we use today, he drew inspiration from a French army captain named Charles Barbier who developed a similar code. Barbier created a nonverbal communication system so his officers could read battle commands during the night without the use of candlelight. This was because the enemy could see their lighted candles and used that to ambush the soldiers. In the late 1800s, Louis Braille refined Barbier’s system and created the foundation for today’s braille code.
For many languages, including English, there are different versions, or “grades,” of braille. 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. Because it’s a code, we can transcribe braille into several dialects including English, Spanish, French, German, and Italian. There are 133 languages that can be written in braille. See the picture with Taiwanese Mandarin language being written in braille.
How is braille written?
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. The dot positions are identified by numbers from one to six (see figure). There are 64 possible combinations, including no dots at all for a word space. Dot configurations can be used to represent a letter, digit, punctuation mark, or even a word. The mappings (the letter or word that a combination of raised dots refers to) vary from language to language.
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. Even within English braille there are 3 levels of braille.

Grade 1 Braille
Grade 1 braille is a letter-for-letter substitution of its printed counterpart. This is the preferred code for beginners because it allows people to get familiar with, and recognize different aspects of, the code while learning how to read braille. English grade 1 braille consists of the 26 standard letters of the alphabet as well as punctuation.

Grade 2 Braille
The literary braille code, grade 2, uses “contractions” that substitute shorter sequences for the full spelling of commonly-occurring letter groups. The contractions are similar to English print contractions, like “cannot” versus “can’t”, in the way that a word is shortened. For example, “the” is usually a single character in braille. We use this type of braille code for a few reasons. 
First, a standard braille cell is large. That means that one page of print can easily turn into three pages of braille. Contractions help reduce the number of characters and thereby reduce the overall size of a document. Second, reading and writing braille can be time-consuming. By implementing contractions, it takes less time to do both.
Grade 2 braille is the most commonly used form of braille code and is found in books, public signage, and restaurant menus to name a few. It consists of the 26 standard letters of the alphabet, punctuation, and contractions.
Grade 3 Braille
It is the last, and certainly least (used), form of literary braille code used within the blind community. Considered braille “shorthand,” this code often compresses entire words into just one or a few characters. There is no official standardization for grade 3 braille and, therefore, official publications do not use it. Instead, it most often appears in personal letters, diaries, and notes.

Six Dots
Six dot positions make up each braille character or “cell”. These dot positions form a rectangle composed of 2 columns with 3 dots in each column. A single dot or any combination of dots may be raised at any of the 6 positions. Counting spaces, in which no dots appear, there are 64 English braille combinations in total. When referencing a braille character, one may describe the positions where dots are raised. Each dot within a cell has a number. Starting in the upper left and moving down, the dots are universally numbered 1 through 6 as seen in the image below.
For example, dots 1-3-4 would describe a cell with three dots raised; the top and bottom cells of the left column and the top cell of the right column. 

Indicators
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 we use certain characters as “prefixes” or “indicators” that affect the meaning of subsequent cells. For example, when a dot 6 falls before a letter, the reader knows it is a capital letter. Without a dot 6, the reader knows it is a lower case letter. In another example, dots 3-4-5-6, called the “numeric indicator”, tells the reader to interpret certain following letters (A through J) as numbers. There is then another character or a space to tell the reader they are switching back to letters.

More about the braille cell
Dot height, cell size, and cell spacing are always uniform. Significant characteristics of the text, such as italics used for emphasis, must be handled by 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.
People read braille by moving the hand or hands from left to right along each line. The reading process usually involves both hands, and the index fingers generally do the reading. The average reading speed is about 125 words per minute. But, greater speeds of up to 200 words per minute are possible.
By using the braille alphabet people who are blind can review and study the written word. They can also become aware of different written conventions such as spelling, punctuation, paragraphing and footnotes.
Most importantly, braille gives blind and vision-impaired individuals access to a wide range of reading materials including recreational and educational reading, financial statements, which are all part of daily adult life. Through braille, people who are blind can also pursue hobbies and cultural enrichment.
Indian currency used to be very blind-friendly with markings embossed on the notes to indicate their value. The newer notes that were introduced after demonetisation are unfortunately not so blind-friendly. Many organisations have been trying to persuade the Reserve Bank of India to make the notes more blind-friendly.

BOX on Louis Braille
Louis Braille was born in the village of Coupvray, France on January 4, 1809. Braille’s father was a leather-worker and poked holes in the leather goods he produced with the awl. Braille lost his sight at a very young age after he accidentally stabbed himself in the eye with his father’s awl. At eleven years old, Braille found inspiration to modify Charles Barbier’s “night writing” code in an effort to create an efficient written communication system for fellow blind individuals. He enrolled at the National Institute of the Blind in Paris one year earlier. He spent the better part of the next nine years developing and refining the system of raised dots that we now know by his name, Braille. While night writing used 12 dots, Braille's code worked with only 6. So just one finger-tip was enough to scan the entire cell unit and so reading could be speeded up.
END OF BOX
Louis Braille’s legacy has enlightened the lives of millions of people who are blind. As a result, blind individuals from all over the world benefit from Braille’s work daily. Today, we transcribe braille code in many different languages worldwide. Louis would be very proud to know his creation has given literacy to countless numbers of people over the decades. Consequently, people who are blind can enjoy all the printed-word has to offer just like everyone else. The effect is tremendously empowering and helps them achieve success in school and their careers.
Many millions in India and the world live without the gift of sight. But by learning braille, they have become independent and can live a full life. Why don't you learn braille too? Send a message to your friend in braille today!
Adapted from many sources