24 Most Popular HTML5 Interview Questions and Answers (2024)

Blog / 24 Most Popular HTML5 Interview Questions and Answers (2024)

HTML is critical for web development.

Most employers consider a solid understand of HTML to be a must have for web developers.

If you're looking to up-skill and get to grips with the basics and more advanced HTML concepts you've come to the right place.

Q1.

What is HTML?

Junior

HTML stands for HyperText Markup Language. It's the standard markup language used to create web pages. HTML is the foundation of all web content, specifying the structure of web pages in a format that web browsers can interpret and display.

Q2.

What are HTML tags?

Junior

HTML tags are the coding elements used to structure and format content on a web page. Each tag is enclosed in angle brackets, like <tagname>, and usually comes in pairs: an opening tag (<tagname>) and a closing tag (</tagname>). Tags can contain attributes for additional functionality.
Exmaple:
- This tag creates a hyperlink; <a> is the tag, href="https://example.com" is the attribute, and "Click here" is the link text displayed to the user.

Q3.

Are HTML tags and elements the same thing?

Junior

HTML tags are the specific codes enclosed in angle brackets (like <p>), used to mark the start and end of an element.
An HTML element is the combination of a start tag, its content, and an end tag (for example, <p>Content</p>). So, while tags form part of an element, an element includes the tags and the content between them.

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Q4.

What is the difference between a block-level element and an inline element?

Junior

Block-level elements start on a new line and occupy the full width available, stacking vertically.
- Examples include <div>, <p>, and <h1>.
Inline elements do not start on a new line and only take up as much width as necessary, lining up horizontally with other content.
- Examples include <span>, <a>, and <img>.

Q5.

What is semantic HTML?

Junior

Semantic HTML involves using HTML elements that clearly describe their meaning and purpose in the webpage, not just their appearance. This approach uses specific tags like <article>, <section>, <header>, <footer>, <nav>, and <aside> to accurately represent different parts and content of a web page. Semantic HTML improves accessibility, search engine optimization, and maintainability of the code.

Q6.

When should you use section, div or article?

Junior

<section>: When you want to group thematically related content. Each <section> should ideally have a heading and represents a standalone section of the document.
<div>: For styling or layout purposes where no other semantic element is appropriate. It's a generic container with no semantic meaning.
<article>: For self-contained, independent content that could be distributed or reused separately, like a blog post, news article, or user comment. Each <article> can contain its own sections and headings.

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Q7.

What are the benefits of server side rendering (SSR) over client side rendering (CSR)?

Junior

Faster Initial Page Load: SSR sends a fully rendered page to the client, leading to quicker initial rendering and improved perceived performance.
SEO Optimization: Search engines can easily index SSR pages as the content is already rendered, improving search rankings.
No JavaScript Dependency: SSR allows users to view content without enabling JavaScript, ensuring accessibility for all users.
Reduced Client-Side Processing: With SSR, most of the heavy lifting is done on the server, reducing the processing load on the client's device.

Q8.

How do you add CSS styling in HTML?

Junior

Inline Styling: Directly in an element's tag using the style attribute.
- Example: <p style="color: blue;">Text</p>.
Internal Styling: Within the <style> tag in the <head> section of the HTML document.
- Example:
External Styling: Linking an external CSS file using the <link> tag in the <head> section.
- Example: <link rel="stylesheet" href="styles.css">

Q9.

What is an iframe and how does it work?

Mid

An iframe (inline frame) is an HTML element that allows embedding another HTML document within a webpage. It works by creating a nested browsing context, essentially embedding a separate page within the parent page.
The basic syntax is <iframe src="URL"></iframe>, where src specifies the URL of the page to be displayed inside the iframe.

Q10.

What is the canvas element in HTML5?

Mid

The <canvas> element in HTML5 is used to draw graphics on a web page via scripting, typically with JavaScript. It creates a fixed-size drawing surface that can be used for rendering graphs, game graphics, art, or other visual images on the fly.
The canvas is a bitmap canvas, rendering pixel-based images, which are resolution-dependent and not scalable like SVG. This element is versatile and powerful for creating dynamic, interactive graphics, but it requires programming to define the graphics.

Q11.

What is the difference between <figure> tag and <img> tag?

Mid

The <img> tag in HTML is used solely for embedding images, while the <figure> tag serves as a container for various types of media, including images, and optionally, their accompanying captions (<figcaption>).
<figure> provides semantic grouping for media elements and their descriptions, enhancing document structure and meaning.
Example:
- While <img> is just for images, <figure> is a semantic element used to encapsulate media elements and their captions, providing additional context or meaning.

Q12.

What is the DOM and how does it work?

Mid

The Document Object Model (DOM) is a programming interface for web documents. It represents the structure of a webpage as a tree of objects, enabling programming languages like JavaScript to manipulate the page's content, structure, and styles.
Changes to the DOM by scripts are immediately reflected in the webpage. The DOM also facilitates event handling for interactive functionality.

Q13.

What does a <DOCTYPE html> do?

Mid

The <!DOCTYPE html> declaration in HTML is used to specify the document type and version of HTML. It tells the browser to render the page in standards mode, ensuring that the page is displayed correctly according to the HTML5 standard.
This declaration must be the first line in an HTML document and is not an HTML tag; it's an instruction to the web browser about what version of HTML the page is written in.

Q14.

What happens when DOCTYPE is not specified?

Mid

When DOCTYPE is not specified in an HTML document, the browser enters "quirks mode." In this mode, the browser uses a different algorithm to interpret the webpage, which often emulates the behavior of older browsers.
Essentially, omitting DOCTYPE may cause a webpage to not adhere to modern web standards, leading to layout issues and poor cross-browser compatibility.

Q15.

What is the significance of <head> and <body> tag in HTML?

Mid

The <head> tag in HTML contains metadata like the page title, links to CSS, and scripts, essential for search engines and browser processing.
The <body> tag encloses the visible content of the webpage, including text, images, and interactive elements, directly seen and interacted with by users. Together, they organize the HTML document into backend information and frontend display.

Q16.

What is the role of the alt attribute in HTML?

Mid

The alt attribute in HTML provides alternative text for images. It serves two main purposes: improving accessibility by describing the image content to screen reader users and displaying a descriptive text in case the image fails to load.
This attribute is crucial for users with visual impairments and for overall web accessibility.

Q17.

How to include JavaScript code in HTML?

Mid

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Q18.

What does CORS stand for and what issue does it address?

Senior

Q19.

Describe the difference between <script>, <script async>, and <script defer>.

Senior

Q20.

Explain the difference between layout, painting and compositing?

Senior

Q21.

What is the difference between HTML and XHTML?

Senior

Q22.

What is the Geolocation API in HTML5?

Senior

Q23.

How will you make an image draggable in HTML5?

Senior

Q24.

Explain the concept of web storage in HTML5.

Senior