Braille pattern dots-12468

The numbers identify dot positions, not a word or number.

An eight-dot cell has two columns of four positions. Read from top to bottom, the left column is numbered 1, 2, 3, 7 and the right 4, 5, 6, 8. In ⢫, the top two positions on the left and the top, third and bottom positions on the right are filled. “Eight-dot” describes the cell's capacity; this pattern has only five filled dots.

Braille is a system for reading and writing through raised dots that can be felt with the fingertips. This text character records one such pattern. Unicode preserves the dot arrangement; the Braille code assigns a letter, punctuation mark or other value. To interpret it in a passage, you need to know which code the passage uses.

Why does Braille have an eight-dot form?

Two extra positions allow more patterns in a single cell.

The familiar six-dot cell has two columns of three positions. Eight-dot Braille adds a position beneath each column, increasing the possible patterns from 64 to 256, including the blank cell. Computer Braille uses that extra capacity to distinguish more characters.

In 1821, Charles Barbier introduced his 12-dot “sonography,” designed for silent night communication, at a Paris school for blind pupils. Louis Braille, a pupil there, developed his six-dot system, published in 1829. By the early 1970s, eight-dot cells were being used for computer Braille.