Braille pattern dots-345678

A shape: six raised dots in an eight-dot Braille cell. Braille cells are numbered by column: dots 1, 2, 3 run down the left, dots 4, 5, 6 down the right, and the extra bottom row adds dot 7 on the left and dot 8 on the right. In ⣼ the whole right column is raised, plus the lower half of the left. Louis Braille built the classic six-dot cell from an earlier raised-dot method Charles Barbier published in 1815; Braille's system was in place by 1824 and printed in 1829. The two extra dots came much later, so computers and Braille displays could show 256 different cells, and Unicode encodes all 256.

A cell only gets a meaning from a Braille code, and each language and purpose has its own table. That is why ⣼ has no fixed letter. Its top six dots, 3-4-5-6, form ⠼, which in English Braille is the number sign; ⣼ adds dots 7 and 8, so it is a different pattern, not the number sign.

Why does it turn up in comments and messages?

Because each Braille cell works as a tiny 2×4 pixel grid. People draw pictures, faces and logos out of Braille characters and paste them into chats, comments and posts; programs also convert images into this kind of text art, and terminal tools use the cells for compact charts. If ⣼ arrives inside a block of similar dots, it is part of a picture, not a word: it shades a spot with the top-left corner left empty. Such art lines up best in a monospaced font on a wide screen and breaks when the text wraps.

Keep blind readers in mind. Many screen readers announce every cell aloud as a Braille pattern, so a large piece of Braille art becomes a long string of dot numbers. A short caption saying what the picture shows helps.