Top 50 HTML Interview Questions & Answers (2025 Edition)

HTML (HyperText Markup Language) is the standard markup language for creating web pages and applications. Below are the top 50 frequently asked HTML interview questions and detailed answers, covering everything from basic tags to semantic elements and SEO practices.

Basics of HTML

1. What is HTML?
HTML stands for HyperText Markup Language. It is used to structure content on the web by defining elements like headings, paragraphs, images, links, and other media. HTML is not a programming language; it’s a markup language that tells the browser how to display content.

2. What are tags in HTML?
Tags are special keywords enclosed in angle brackets, e.g., <p> or <div>, used to define and display elements. Most tags come in pairs: an opening tag <p> and a closing tag </p>.

3. What is the difference between HTML and HTML5?
HTML5 is the latest version of HTML with new semantic elements (<article>, <section>), multimedia support (<audio>, <video>), APIs (Canvas, Geolocation), and mobile-friendly enhancements. It replaces older plugins like Flash.

4. What are HTML attributes?
Attributes provide additional information about HTML elements. They are always specified in the opening tag and come in name/value pairs like href="https://example.com".

5. What is the DOCTYPE declaration?
The <!DOCTYPE html> declaration defines the document type and version of HTML used. It helps the browser render the page in standards mode. For HTML5, the declaration is simply:

<!DOCTYPE html>

6. What are void (self-closing) elements in HTML?
Void elements are those that don’t need a closing tag. Examples include <br>, <img>, <input>, <hr>, and <meta>.

7. What is the difference between block-level and inline elements?

  • Block-level elements (e.g., <div>, <p>, <section>) start on a new line and take up full width.
  • Inline elements (e.g., <span>, <a>, <strong>) stay within the same line and take up only the space they need.

8. How do you create a hyperlink in HTML?
Use the <a> tag with an href attribute:

<a href="https://example.com">Visit Example</a>

9. How can you insert an image in HTML?
Use the <img> tag with the src (image path) and alt (alternative text) attributes:

<img src="logo.png" alt="Company Logo">

10. How do you create a list in HTML?
Use <ul> (unordered), <ol> (ordered), and <li> for list items:

<ul>
  <li>Item 1</li>
  <li>Item 2</li>
</ul>

Intermediate to Advanced HTML

11. What is semantic HTML?
Semantic HTML uses tags that clearly describe their meaning in a human- and machine-readable way. For example, <article>, <footer>, <nav>, and <header> are all semantic tags. They help improve SEO, accessibility, and code readability.

12. What is the purpose of the <meta> tag in HTML?
The <meta> tag provides metadata about the HTML document, such as character set, page description, author, and viewport settings for responsive design.

Example:

<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">

13. How do you add a comment in HTML?
HTML comments are added using:

<!-- This is a comment -->

They are ignored by the browser and useful for code documentation.

14. What is the <div> tag used for?
The <div> (short for division) is a block-level element used as a container to group other HTML elements. It’s commonly used with CSS or JavaScript for layout and styling.

15. What is the <span> tag used for?
The <span> tag is an inline container used to group text for styling or scripting. Unlike <div>, it doesn’t start on a new line.

16. How can you embed a video in HTML?
You can embed videos using the <video> tag with src, controls, autoplay, loop, etc.:

<video src="video.mp4" controls></video>

This is part of HTML5 and replaces the need for external plugins.

17. What are data- attributes in HTML5?*
These are custom attributes used to store extra information on HTML elements:

<div data-user-id="12345"></div>

You can access them via JavaScript using dataset, e.g., element.dataset.userId.

18. What is the difference between <strong> and <b>, or <em> and <i>?

  • <strong> and <em> convey semantic importance (important and emphasized text) and are better for accessibility.
  • <b> and <i> are purely visual (bold and italic).

19. How do you create a table in HTML?
Use <table>, <tr> (table row), <th> (table header), and <td> (table data):

<table>
  <tr>
    <th>Name</th>
    <th>Age</th>
  </tr>
  <tr>
    <td>Alice</td>
    <td>25</td>
  </tr>
</table>

20. How do you make a form in HTML?
Use the <form> tag with input elements like <input>, <textarea>, <select>, and <button>:

<form action="/submit" method="POST">
  <input type="text" name="username">
  <input type="submit" value="Submit">
</form>

Advanced HTML & SEO Optimization

21. How do you make a webpage SEO-friendly using HTML?
Use semantic tags (<article>, <header>, <footer>, <nav>), relevant meta tags (description, keywords, robots), heading hierarchy (<h1> to <h6>), alt attributes for images, and canonical URLs.

22. What is the <section> tag used for?
It defines sections in a document, like chapters or grouped content. Helps improve accessibility and SEO.

23. What’s the difference between <article> and <section>?

  • <article> is for self-contained, reusable content (blog post, news article).
  • <section> is for grouping related content inside a page.

24. What is the use of <nav> tag in HTML?
It defines navigation links. It helps screen readers and search engines identify the main site navigation.

25. What is the <aside> tag used for?
Displays content indirectly related to the main content (e.g., ads, sidebars, related posts).

26. How does the <header> tag work?
It defines a header section for a document or section. Typically contains site name, logo, or main navigation.

27. How does the <footer> tag work?
It defines the footer of a document or section. Usually includes contact info, copyright, and links.

28. How does the <main> tag enhance accessibility?
It indicates the main content area. Assistive technologies can skip repetitive content and jump directly to this area.

29. What is the purpose of the <mark> tag?
Highlights text with a yellow background. It’s useful for search results or emphasizing keywords:

<p>This is a <mark>highlighted</mark> word.</p>

30. How do you open links in a new tab?
Use the target="_blank" attribute in an anchor tag:

<a href="https://example.com" target="_blank">Visit</a>

31. What is the difference between relative and absolute URLs in HTML?

  • Relative URL: /images/pic.jpg (depends on the page location)
  • Absolute URL: https://example.com/images/pic.jpg (complete path)

32. What is the use of the <base> tag?
Specifies a base URL for all relative links in the document. It must be placed inside <head>.

<base href="https://example.com/">

33. What is a favicon and how to include it?
A small icon shown in the browser tab. Add it in the <head>:

<link rel="icon" href="favicon.ico" type="image/x-icon">

34. How do you include external stylesheets?
Using the <link> tag in the <head> section:

<link rel="stylesheet" href="styles.css">

35. What is lazy loading in HTML5?
Defers the loading of images until they are needed (i.e., in the viewport), improving page speed:

<img src="image.jpg" loading="lazy" alt="Lazy Loaded Image">

36. What’s the purpose of <noscript> tag?
Displays alternative content for users with JavaScript disabled.

37. How do HTML5 APIs enhance web pages?
APIs like Geolocation, Canvas, Drag-and-Drop, Web Storage, and WebSockets add dynamic functionality to web pages.

38. What is the <canvas> element in HTML5?
Used to draw graphics on the fly using JavaScript. Common for games, charts, or custom drawing apps.

39. What are ARIA roles in HTML?
ARIA (Accessible Rich Internet Applications) roles enhance accessibility by describing the behavior of elements to assistive technologies.

40. How do you embed audio or video in HTML5?
Use <audio> or <video> tags with controls:

<audio controls>
  <source src="song.mp3" type="audio/mpeg">
</audio>

<video controls>
  <source src="video.mp4" type="video/mp4">
</video>

41. What is the <track> tag used for in <video> or <audio>?
Adds subtitles or captions:

<track src="subtitles.vtt" kind="subtitles" srclang="en" label="English">

42. How do you create a progress bar in HTML5?
Use the <progress> element:

<progress value="70" max="100"></progress>

43. What is the <meter> tag used for?
Represents scalar measurements like disk usage or strength levels:

<meter value="0.6">60%</meter>

44. How do you optimize your HTML for performance?
Minify HTML, defer non-critical resources, use lazy loading, remove unused code, reduce DOM depth, and load scripts asynchronously.

45. What’s the use of rel="canonical" in a <link> tag?
Avoids duplicate content issues by pointing to the preferred URL for a page:

<link rel="canonical" href="https://example.com/page">

46. How do you add tooltips to elements in HTML?
Use the title attribute:

<button title="Click to submit">Submit</button>

47. What is the purpose of the viewport meta tag?
Ensures responsive design by controlling layout on mobile browsers:

<meta name="viewport" content="width=device-width, initial-scale=1.0">

48. What is the difference between <b> and <strong>?

  • <b> is for visual bolding.
  • <strong> has semantic meaning (important text).

49. How do you make a website multilingual using HTML?
Use the lang attribute in the <html> tag and mark specific sections with correct lang values:

<html lang="en">
<p lang="fr">Bonjour</p>

50. What is the role of structured data in HTML for SEO?
Structured data (using JSON-LD or Microdata) helps search engines understand page content and enhance results with rich snippets.

<script type="application/ld+json">
{
  "@context": "https://schema.org",
  "@type": "WebPage",
  "name": "Top HTML Interview Questions"
}
</script>

These top 50 HTML questions and answers will help you confidently prepare for technical interviews and optimize your HTML skills for modern, SEO-friendly web development.

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