What the shades and eighth-blocks actually are
These live in Unicode's Block Elements range. โ is the light shade (25% fill), โ the medium shade (50%), and โ the dark shade (75%), while โ is a fully filled cell. The remaining glyphs are precise fractions: โ is seven-eighths, โ three-quarters, โ five-eighths, โ a half, โ three-eighths, โ a quarter, and โ one-eighth wide, with โ filling the right half. Because each is a fixed-width monospace cell, they line up perfectly in code editors and terminals, which is exactly why they render solid graphics out of plain text.
Building bars and art with them
The classic use is a text progress bar: string full blocks against light shade, like โโโโโโโโโโ 50%, and paste it into a Discord status, a README, or a spreadsheet cell. The eighth-block widths let you fake anti-aliased edges, so a bar can end at a fraction rather than a whole cell. Streamers post loading meters in chat this way, and coders build boxed menus and gradients for TUIs. Try pasting โโโ as a fade at the edge of a banner, or stack rows of โ to spell blocky letters in a monospace font.