Bold (SGR 1)

Category: sgr · Tags: ECMA-48 Standard, VT100 · Specification ↗

SGR 1 activates bold text rendering. The sequence is ESC [ 1 m. Bold is one of the original VT100 text attributes and is universally supported across terminals. Historically, some terminals render SGR 1 as increased intensity (brighter color) rather than heavier font weight — and some do both. When bold is active alongside one of the standard foreground colors (SGR 30-37), certain terminals will substitute the corresponding bright color (SGR 90-97). This means bold red may appear as bright red rather than bold red, depending on the terminal and its configuration. Bold is reset by SGR 0 (reset all) or SGR 22 (reset bold/dim). Note that SGR 22 resets both bold and faint — there is no way to reset one without the other.

Supported by 6 of 6 backends (100%)

Support Matrix

Backend	Version	Support	Notes
Alacritty	0.26.0	✓ yes
Ghostty	1.3.1	✓ yes
Kitty	0.40.0	✓ yes
vt100	0.1.0	✓ yes
WezTerm	0.1.0-fork.5	✓ yes
xterm.js	5.5.0	✓ yes

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