As a full-stack or front-end web developer, knowing how to properly underline text in HTML is an important formatting skill. Underlined text can help highlight key points, differentiate links or glossary terms, denote edits on printed pages, and more.
But with HTML‘s separation of structure and presentation, what‘s the right semantic way to underline text today? As a core web formatting technique, underlining text deserves an in-depth look from a modern web developer perspective.
The Purpose of Underlined Text
Before digging into the code, why bother underlining text on web pages in the first place? Some common use cases include:
- Highlighting key words, phrases, or passages to attract user attention
- Denoting glossary terms or acronym expansions inline
- Identifying links embedded in body text visually
- Indicating edits and changes from a printed draft
- Stylistically setting apart proper names or citations
- Flagging spelling or grammar errors in the text
However, underlining should typically be used sparingly. Overuse diminishes its ability to attract user interest. Too much underlined text can seem distracting, messy, or confusing. Light underlines on bright backgrounds can also suffer accessibility problems if contrast turns weak.
Many UX designers consider underlines most appropriate for glossary terms, uncommon names, inline links, or occasional emphasis. Paragraphs or long passages of fully underlined text is rarely ideal on modern pages.
Brief History of the HTML <u> Element
The original means of underlining text on the web was the <u> element in early HTML specifications. It was intended to represent text with an alternative presentation or meaning compared to surrounding content.
This included things like:
- Proper names in Chinese text
- Phrase or word indicators in other languages
- Miscellaneous additional meanings in poetry or citations
- Spelling or grammatical errors
Style guides at the time discouraged using <u> simply for styling importance since other structures like <em> or <strong> better served that purpose.
But <u> saw inconsistent browser support and fell out of common use in HTML 4 and XHTML in favor of purely CSS-based styling. Cascading style sheets allowed greater control over rendering.
In HTML5, however, the <u> tag returned as a "phrasing content" element representing text that is stylistically offset, non-textual, or otherwise distinct from surrounding content. This brought back a semantic HTML option for underlining text.
Underlining With the <u> Element
Thanks to HTML5 reinstating it, using the <u> tag remains one of the simplest ways to underline pieces of inline text:
<p>This paragraph features some <u>underlined</u> text enclosed in <u> tags.</p> The browser renders all text within the <u> element with an underline by default:
This paragraph features some underlined text enclosed in <u> tags.
To underline entire text blocks or passages simply wrap the full content in <u> tags:
<u>
<p>This entire block will render with underscoring applied to all text inside it.</p>
<p>The underline formatting stretches across both paragraphs enclosed by the tags.</p>
</u>Advantages of using the HTML <u> element:
- Semantic meaning – Indicates stylistic separation from surrounding text
- Ease of use – Simple syntax for quick inline underlining
- Adaptive rendering – Browsers handle styling details for you
But this simplicity also comes with key downsides:
- Limited customization – Can‘t tweak underline style, color, etc.
- Poor browser support in older versions
- Suboptimal for non-inline usage cases
While handy for quick underlining, more flexible approaches do exist.
Using the text-decoration Property
For greater customization of underlined text, CSS delivers expanded options through the text-decoration property and related styles.
The text-decoration property allows underline styling directly through a style sheet ruleset:
p {
text-decoration: underline;
}You can mix this with other text formatting like bold or italics by chaining decorations:
p {
text-decoration: underline;
font-weight: bold;
font-style: italic;
}Text styled this way renders with flexible combinations of formatting while keeping content semantically separate through CSS:
This flexibly formatted text keeps semantics intact.
Consider enhancing link underlines using custom text decoration too:
a {
text-decoration: underline wavy rgba(0,0,255,.6);
}a {
text-decoration: underline wavy rgba(0,0,255,.6);
}
Customizations this way go beyond anything possible with <u> alone:
- Underline color
- Underline thickness
- Underline style – solid, dotted, dashed, double, etc.
You also get more options for selectively applying underlines only where semantically needed:
.key-term {
text-decoration: underline;
}Where supported, text-underline-position further adapts render positioning.
The CSS approach wins ecosystems with greater feature support like underline style, color, and positional control. This lets developers hand-tune underline presentation in ways no HTML element could accomplish alone.
Using Borders for Underlines
If you need even more customization for underlined passages, consider leveraging borders instead as an extra approach:
.bordered {
border-bottom: red dotted .2em;
}Borders along the text baseline visually emulate an underline with expanded flexibility for stylesheet control over things like:
- Border color
- Border thickness
- Border style
- Mixing with other text formatting
Border-based underlines even work on more complex groupings like grid or table structures which text formatting cannot reach.
However, this loses the semantic meaning of a standard text underline in return for greater presentation options. Accessibility considerations come into play if solely relying on visual borders to emphasize key text passages.
Still, combined with proper text semantics using CSS classes, borders give developers maximum reign over visual treatment. These even permit adding other borders or mixing underscore styles like double lines:
This paragraph mixes a bold double border underline for extra impact!
HTML elements can‘t achieve that level of versatility alone. But be thoughtful incorporating it with other text if muddling meaning for users.
Browser Support and Accessibility Implications
Considering browser and device support helps guide decisions between techniques. Underlines also affect how readable text remains for those with visual impairments.
Browser Support
| Method | Overall Browser Support | Notes |
|---|---|---|
| <u> | IE6+, Firefox 1+, Chrome 1+, Safari 1+, iOS Safari 1+, Opera 4+ |
|
| text-decoration | IE6+, Firefox 1+, Chrome 1+, Safari 1+, iOS Safari 1+, Opera 3.5+ |
|
| borders | IE4+, Firefox 1+, Chrome 1+, Safari 1+, iOS Safari 1+, Opera 3.5+ |
|
CSS-based text formatting enjoys nearly universal browser support today while still adding customization options. For the broadest device/user reach, emphasize those techniques over HTML-only approaches.
Accessibility Considerations
Proper contrast ratios become vital for underline readability by those with low vision conditions. Light underlines against bright backgrounds easily fail minimum thresholds.
Heading styles with thick/bold single underlines generally provide the most accessible renders. But customized CSS and border underscoring require extra testing in screen readers to ensure text is understandable when styles are turned off or colors inverted.
HTML Specifications advise using CSS text-decoration for underlined hyperlinks of edits rather than <u> alone to safeguard adaptive text styling in more user agents.
So while <u> has semantic meaning, lean on cautious CSS usage with sufficient contrast and screen reader testing to make all underlines broadly usable.
Best Practices for Web Developers
Based on the options available today, what are some best practices for responsibly underlining text in HTML?
Use Semantic HTML Tags First
Elements like <em> or <strong>will often suit indicating document importance or word stress better than presentational underlines alone.
Prefer CSS Over<u> for Styling Flexibility
The CSS text-decoration property affords greater customization like underline color or style changes over HTML-only approaches.
Use Borders Judiciously for Unique Effects
While tempting for custom underlining, border-based approaches risk muddling meaning for some users if leaned on too heavily.
Test Accessibility Thoroughly
Ensure underline colors and styles remain readable for vision impaired users. Verify screen reader comprehension.
Underline Infrequently and Minimally
Overuse undermines effectiveness! Keep key word/phrase usage short and selective.
Avoid Entire Paragraphs or Passages
Full multi-line underlining becomes taxing and overwhelming fast. Use sparingly.
Following these coding and design principles will help keep underlined text clean, accessible, and useful for the broadest range of web projects.
Putting Underline Knowledge to Work
As a developer, when should you break out underlining text in practice?
Denote Glossary Terms On First Use
Introduce reader-unfamiliar vocabulary uniquely against body text.
Link Document References or Citations
Set apart footnotes, bibliography entries, table sources inline.
Flag Spelling/Grammar Errors in Draft Docs
Call attention to fixes needed if printing working copies.
Stylistically Separate Proper Names
Offset distinctive names/terms using common document conventions.
Emphasize Without Overwhelming
Accentuate critical phrases which deserve close attention from proficient readers.
Follow those principled use cases, and underlined text can boost document utility for users without much downside.
But utilize underscores wisely across headings, links, citations, and body content! No matter which approach you lean on, restraint remains key.
Related Text Formatting Options
Beyond underlining, HTML and CSS provide additional ways to emphasize and style important text:
Bold Text – Use the <b>, <strong>, or font-weight tags to make text boldface.
Italic Text – The <i>, <em>, and font-style properties let text italicize.
Strikethrough Lines – Cross out text like edits using <s>, <del>, or text-decoration line-through.
Contrasting Color – Employ color styles to make passages stand out.
CAPITAL LETTERS – Capitalizing attracts user attention in small doses.
Highlighted Backgrounds – Use background colors for text selected against page colors.
With all text formatting changes, balance attracting interest against overusing effects!
In Closing: A Toolkit for Responsible Underlining
This deep dive on the various methods for underlining text explored the original <u> element, CSS text-decoration extensions, border-based underscoring, browser support nuances, accessibility considerations, real-life use cases, and more.
Armed with these thorough technical insights, web developers can pick the right tool for any project need!
Whether using <u> tags for quick notation, tweaking text underline styles globally through CSS, or selectively applying border underscoring, engineers today have options aplenty. Even setting aside presentational usage, text underlining retains legitimate semantic purpose identifying editorial changes, annotations, terms requiring special indication.
But restraint and user testing is key whichever approach you pick. Used judiciously, underlines highlight without overwhelming readers. Thanks for reading this guide! Let me know in the comments if you have any other questions on formatting text with HTML.