- Braille
Braille is a system of raised dots that can be read with the fingers by people who are blind or who have low vision. World Braille Day is annually celebrated on January 4, the birthday of Braille inventor.
Who and how it is developed:
Louis Braille was born in 1809, though he was not born as blind he lost his sight when he was 3-years old. But things were going well when Louis got a scholarship to the Royal Institution for Blind Youth in Paris, when he was 10. But even there, most of the teachers just talked at the students. The library had 14 huge books with raised letters that were very hard to read and Louis became impatient.
He later meet a former soldier named Charles Barbier, who used,” a code of 12 raised dots that let soldiers share top-secret 
information on the battlefield without even having to speak. Louis inspired from it and developed a new way of system for reading for blinds. Louis trimmed Barbier’s 12 dots into 6, ironed out the system by the time he was 15, then published the first-ever braille book in 1829. In 1837, he added symbols for math and music. But since the public was skeptical, blind students had to study braille on their own. Even at the Royal Institution, where Louis taught after he graduated, braille wasn’t taught until after his death. Braille began to spread worldwide in 1868, when a group of British men, now known as the Royal National Institute for the Blind, took up the cause.
How it looks like:
Braille Alphabet
Braille Number:
How the system is graded:
Grade 1 Braille: Grade 1 braille consists of the 26 standard letters of the alphabet and punctuation. It’s mainly used by people who just started reading braille.
Grade 2 Braille: Grade 2 braille consists of the 26 standard letters of the alphabet, punctuation and contractions. Books, public signage, restaurant menus, and most other braille materials are written in Grade 2 braille.
Grade 3 Braille: Grade 3 is the last form of braille and is used the least in within the blind community. It is considered to be braille “shorthand”, with entire words shortened to only one or just a few letters. Grade 3 braille has never been standardized so it is not used in any official publications. Instead it is most often used only in personal letters, diaries, and notes.
Conclusion:
Now practically every country in the world uses braille. Braille books have double-sided pages, which saves a lot of space. Braille signs help blind people get around in public spaces. And, most important, blind people can communicate independently, without needing print.
Reference:
1) Braille works: Available online at: https://brailleworks.com/braille-resources/braille-alphabet/ ;refered
2) AFB American foundation for the blind: available online at : http://braillebug.afb.org/braille_print.asp