Deprecated HTML Tags Test

What is it?

Deprecated HTML tags are elements that have been removed from the modern HTML specification because their job is now better handled by CSS, which separates structure from presentation and produces markup that is easier to maintain and restyle. Tags such as <font>, <center>, <marquee>, and <blink> were retired for exactly that reason. This test scans the page being checked for any of these legacy elements so you know which ones still need replacing with their modern equivalents.

Why deprecated tags still matter

Browsers still render most deprecated tags so legacy pages do not break, but that support is not guaranteed indefinitely. A page that depends on deprecated markup is one browser update away from rendering incorrectly, which is a particularly bad outcome on a commercial site where the visual appearance is part of the brand. Replacing the tags with modern equivalents protects the page against that risk and produces cleaner, more maintainable markup at the same time.

Beyond compatibility, deprecated tags are often a signal of older code that has accumulated other technical debt. A page using <font> in 2026 was probably authored years ago and may also lack semantic structure, accessibility features, responsive layout, and modern image formats. Auditing for deprecated tags often becomes a useful entry point for a broader modernization effort on legacy templates.

Common deprecated tags and their modern replacements

<font>, <center>, <marquee>, <blink>: replace with semantic elements styled in CSS.
<b> and <i> for emphasis: prefer <strong> and <em>, which carry semantic weight.
Presentational attributes such as bgcolor, align, and border: move to CSS.
<frameset> and <frame>: rebuild the layout with modern CSS, and only use <iframe> when truly necessary.

This test surfaces every deprecated element it detects on the page so you know exactly what needs replacing. The fix guide below walks through modern equivalents, CSS-based replacements for presentational attributes, and how to update legacy templates in the major content management systems.

Pass rate:

Top 100 websites: 94%
This value indicates the percent of top 100 most visited websites in the US that pass this test (in the past 12 months).
All websites: 92%
This value indicates the percent of all websites analyzed in SEO Site Checkup (500,000+) in the past 12 months.

Pass rates of Top 100 US websites
2021	99%
2022	92%
2023	94%
2024	94%

100

How do I fix it?

This test fails when the page uses HTML elements that are no longer part of the current HTML specification. Deprecated tags may still render in today's browsers, but support can be dropped at any time and most have semantically richer modern replacements. Fixing this issue means swapping legacy tags for current equivalents and moving presentation concerns into CSS.

Example

<!-- Deprecated -->
<font color="red">Important</font>
<center>Centered text</center>

<!-- Modern equivalent -->
<span style="color: red;">Important</span>
<p style="text-align: center;">Centered text</p>

Where to make the change

Raw HTML: search the codebase for the deprecated tag names and replace each occurrence with a semantic element styled via CSS.
WordPress: deprecated tags often live in classic-editor posts or custom theme templates. Open the offending post or template and replace the legacy markup; the block editor will not introduce new ones.
Shopify, Wix, or Squarespace: issues usually trace to custom HTML embeds. Edit the embed to use modern tags and CSS.

Common causes and how to resolve them

<font>, <center>, <marquee>, <blink>: replace with semantic tags styled in CSS.
<b> and <i> for emphasis: use <strong> and <em>, which carry semantic weight that <b> and <i> do not.
Presentational attributes such as bgcolor, align, border: move them to CSS so the markup stays clean.
Old <frameset> or <frame> markup: rebuild the layout with CSS and, if absolutely necessary, <iframe>.

Best practices

Use semantic HTML5 elements: <header>, <nav>, <main>, <article>, <section>, and <footer> describe meaning, which helps both SEO and accessibility.
Keep presentation in CSS: markup describes structure and meaning; CSS handles visuals. This separation makes the site easier to redesign.
Validate with a current HTML checker: running the page through an HTML validator catches deprecated tags and other markup issues before they ship.