What ─ means
It draws a light horizontal edge.
If you ask how to make a box in text, repeat ─ for the rule, then add corners such as ┌ and └ or a junction such as ┼.
It was not invented alone. The set comes from compatibility standards used before 1990, later familiar from PC text art of the 1980s and early 1990s.
Don't confuse it with
2Combination ideas
2A horizontal divider text rule.
Top edge of a light text box.
Questions people ask
1Why do my box drawing lines look broken?
Mismatched font or spacing. Use a monospace font with midpoint joins and fixed cells.
How to type ─
Windows (Word)
Alt+XType 2500, then Alt+X to get ─.
Windows
Win+Rrun charmap for the full table, or use the emoji picker's Ω symbols tab (Win + .).
macOS
Control+Command+SpaceOpen the character viewer and search “box drawings light horizontal”.
Linux
Ctrl+Shift+UType 2500, then Enter or Space.
HTML
─CSS
\2500Copy-paste
Copy it from the palette above; use U+2500 Unicode input for many cells.
Codes and encoding1 code points
HTML decimal
─
HTML hex
─
CSS content
content: "\2500";
Each escape is closed by the next backslash; a trailing space is needed before a literal hex digit.
URL encoded
%E2%94%80
1
On screen
1
Code points
1
JS .length
3
UTF-8 bytes
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.