On January 4th 1809, Louis Braille was born. Having damaged one eye in an accident as a child, he was completely blind by the age of 5. He attended one of the first blind schools in the world where he learned of a communication system devised by Captain Barbier of the French army. This inspired Braille to come up with a system of his own- and this is the system that people use today.
You can find out more about Louis Braille and the system he created on the Royal Blind website https://www.royalblind.org/
It is also worth having a look at Booktrust's 'What's the Story?' project: http://www.booktrust.org.uk/books/children/bookmark/whats-the-story/