First suggested by User:Kwamikagami by this edit, this template creates a double underline/underscore beneath a string, instead of a single one. It may be used in cases where a single underline is confusing, such as when underlining CJK characters.

A second parameter can be added to specify the color (in name or in hex code, defaults to #000), for example,

<span style="color:red;">Hello {{double underline|world}}!</span>

yields

Hello world!

whereas

<span style="color:red;">Hello {{double underline|world|red}}!</span>

yields the better-looking

Hello world!

For strings within certain {{lang}} templates (such as zh), strings within <big> tags or <code> tags, and some others, this may show up as a thick underline instead of a double underline (depending on your browser settings):

{{lang|zh|好好儿学习,{{double underline|天天}}向上!}}

yields

好好儿学习,天天向上!

<big>Hello {{double underline|world}}!</big>

yields

Hello world!