Bold, Underline, Italic and the rest
To make text bold with SVG, set the weight of the font with font-weight="bold". The font-weight can also be set to 100, 200, ... 900 with higher values corresponding to a greater "boldness."
<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg viewBox = "0 0 500 300" version = "1.1">
<desc>
Text example
</desc>
<g fill = "navy">
<text x = "10" y = "25" font-size = "20">
<tspan font-family = "serif">
Normal weight.
</tspan>
<tspan x = "10" dy = "20" font-family = "serif" font-weight = "bold">
Bold type.
</tspan>
<tspan x = "10" dy = "20" font-family = "serif" font-weight = "100">
font-weight set to 100.
</tspan>
<tspan x = "10" dy = "20" font-family = "serif" font-weight = "200">
font-weight set to 200.
</tspan>
<tspan x = "10" dy = "20" font-family = "serif" font-weight = "600">
font-weight set to 600.
</tspan>
<tspan x = "10" dy = "20" font-family = "serif" font-weight = "700">
font-weight set to 700.
</tspan>
<tspan x = "10" dy = "20" font-family = "serif" font-weight = "900">
font-weight set to 900.
</tspan>
</text>
</g>
</svg>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg viewBox = "0 0 500 300" version = "1.1">
<desc>
Text example
</desc>
<g fill = "navy">
<text x = "10" y = "25" font-size = "20">
<tspan font-family = "serif">
Normal weight.
</tspan>
<tspan x = "10" dy = "20" font-family = "serif" font-weight = "bold">
Bold type.
</tspan>
<tspan x = "10" dy = "20" font-family = "serif" font-weight = "100">
font-weight set to 100.
</tspan>
<tspan x = "10" dy = "20" font-family = "serif" font-weight = "200">
font-weight set to 200.
</tspan>
<tspan x = "10" dy = "20" font-family = "serif" font-weight = "600">
font-weight set to 600.
</tspan>
<tspan x = "10" dy = "20" font-family = "serif" font-weight = "700">
font-weight set to 700.
</tspan>
<tspan x = "10" dy = "20" font-family = "serif" font-weight = "900">
font-weight set to 900.
</tspan>
</text>
</g>
</svg>
The text-decoration attribute can be set to "underline" to underline text.
<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg viewBox = "0 0 500 300" version = "1.1">
<desc>
Text example
</desc>
<g fill = "navy">
<text x = "10" y = "25" font-size = "20">
<tspan x = "10" y = "20" text-decoration = "underline">
Underline turned on by text-decoration.
</tspan>
<tspan x = "10" y = "80" text-decoration = "overline">
Overline turned on by text-decoration.
</tspan>
<tspan x = "10" y = "140" text-decoration = "line-through">
Line-through turned on by text-decoration.
</tspan>
<tspan x = "10" y = "200" text-decoration = "line-through,underline">
Several decorations turned on at once.
</tspan>
</text>
</g>
</svg>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg viewBox = "0 0 500 300" version = "1.1">
<desc>
Text example
</desc>
<g fill = "navy">
<text x = "10" y = "25" font-size = "20">
<tspan x = "10" y = "20" text-decoration = "underline">
Underline turned on by text-decoration.
</tspan>
<tspan x = "10" y = "80" text-decoration = "overline">
Overline turned on by text-decoration.
</tspan>
<tspan x = "10" y = "140" text-decoration = "line-through">
Line-through turned on by text-decoration.
</tspan>
<tspan x = "10" y = "200" text-decoration = "line-through,underline">
Several decorations turned on at once.
</tspan>
</text>
</g>
</svg>