HTML <u> tag
In HTML4.01, the <u> tag was used to underline a text.
Later, it was deprecated in HTML4.
It was obsolete in HTML5 also but later reintroduced with another specific purpose to check the spelling mistake or misspell texts.
CSS Default Value
How Browser will display
Difference between HTML4.01, XHTML and HTML5
|Deprecated in HTML4.01||NA||Reintroduced in HTML5|
Attributes used with <u> tag
The <u> tag supports Global attributes.
The <u> tag supports Event attributes.
<span>, <strong> & <b> tags.