HTML u element

The <u> HTML element represents a span of inline text which should be rendered in a way that indicates that it has a non-textual annotation. This is rendered by default as a single solid underline, but may be altered using CSS.

Warning: This element used to be called the “Underline” element in older versions of HTML, and is still sometimes misused in this way. To underline text, you should instead apply a style that includes the CSS text-decoration property set to underline.

Along with other pure styling elements, the original HTML Underline (<u>) element was deprecated in HTML 4; however, <u> was restored in HTML 5 with a new, semantic, meaning: to mark text as having some form of non-textual annotation applied.