Skip to main content

HTML5 Interview Questions - 2025 Edition

🏗️ HTML Fundamentals​

  1. DOCTYPE Declaration - Purpose & Impact
  2. HTML Document Structure (html, head, body)
  3. HTML Elements vs Tags vs Attributes
  4. HTML5 vs Previous Versions (XHTML, HTML4)
  5. Character Encoding (UTF-8, charset)
  6. HTML Validation & Standards Compliance
  7. Case Sensitivity in HTML
  8. HTML Comments & Conditional Comments

🎯 HTML5 Semantic Elements​

  1. Semantic HTML5 Tags (header, nav, main, section, article, aside, footer)
  2. Document Outline & Heading Hierarchy (h1-h6)
  3. Landmark Roles & ARIA
  4. Figure & Figcaption Elements
  5. Time Element & Datetime Attribute
  6. Address Element
  7. Details & Summary Elements
  8. Mark Element for Highlighting

📦 Element Types & Display​

  1. Block vs Inline vs Inline-Block Elements
  2. Replaced vs Non-Replaced Elements
  3. Void Elements (Self-Closing Tags)
  4. Container vs Content Elements
  5. Flow Content vs Phrasing Content
  6. Interactive Content Elements

🔗 Links & Navigation​

  1. Anchor Tags & Link Types
  2. Button vs Link - When to Use Which
  3. Link Relationships (rel attribute)
  4. Target Attribute & Security (_blank, noopener, noreferrer)
  5. Download Attribute
  6. Navigation Best Practices

📝 Forms & Input Elements​

  1. HTML5 Form Elements (form, fieldset, legend)
  2. Input Types (text, email, password, number, date, etc.)
  3. Form Validation (required, pattern, min, max)
  4. Custom Validation Messages
  5. Form Attributes (action, method, enctype)
  6. Label Association & Accessibility
  7. Datalist & Autocomplete
  8. Form Security (CSRF tokens)

🎬 Media Elements​

  1. Audio Element & Attributes
  2. Video Element & Attributes
  3. Source Element & Media Queries
  4. Track Element for Subtitles/Captions
  5. Picture Element & Responsive Images
  6. Image Optimization (srcset, sizes)
  7. Lazy Loading Images (loading="lazy")
  8. WebP, AVIF Image Formats

🧠 Meta Tags & Document Head​

  1. Meta Charset & Viewport
  2. Meta Description & Keywords
  3. Open Graph Meta Tags
  4. Twitter Card Meta Tags
  5. Canonical URLs
  6. Meta Robots & SEO Directives
  7. Theme Color & Manifest
  8. Favicon & Apple Touch Icons

⚡ Performance & Loading​

  1. Script Loading (async, defer, module)
  2. Resource Hints (preload, prefetch, preconnect, dns-prefetch)
  3. Critical Resource Prioritization
  4. Lazy Loading Strategies
  5. Image Optimization Techniques
  6. Web Font Loading (font-display)
  7. Bundle Splitting & Code Splitting
  8. Service Worker Caching

🔍 SEO & Accessibility​

  1. SEO Best Practices in HTML
  2. Structured Data (JSON-LD, Microdata)
  3. ARIA Labels & Roles
  4. Screen Reader Compatibility
  5. Keyboard Navigation
  6. Color Contrast & Visual Accessibility
  7. Alt Text for Images
  8. Skip Links & Focus Management

💾 Storage & APIs​

  1. Local Storage vs Session Storage vs Cookies
  2. IndexedDB for Complex Data
  3. Web Storage Security
  4. Cookie Attributes (HttpOnly, Secure, SameSite)
  5. Storage Events
  6. Cache API

🌐 Modern Web APIs​

  1. Geolocation API
  2. Notification API
  3. File API & FileReader
  4. Drag and Drop API
  5. History API (pushState, replaceState)
  6. Intersection Observer API
  7. Mutation Observer API
  8. Web Workers & Service Workers
  9. WebRTC API
  10. Payment Request API

🔒 Security​

  1. XSS (Cross-Site Scripting) Prevention
  2. CSRF (Cross-Site Request Forgery) Protection
  3. Content Security Policy (CSP)
  4. Subresource Integrity (SRI)
  5. HTTPS & Mixed Content
  6. Input Sanitization
  7. Clickjacking Prevention

📱 Progressive Web Apps​

  1. Web App Manifest
  2. Service Worker Lifecycle
  3. App Shell Architecture
  4. Push Notifications
  5. Background Sync
  6. Install Prompts
  7. Offline Functionality

🎨 Advanced HTML5 Features​

  1. Web Components (Custom Elements)
  2. Shadow DOM
  3. HTML Templates & Slots
  4. Canvas Element & 2D Context
  5. SVG Integration
  6. MathML Support
  7. WebGL & 3D Graphics

🔧 Development & Debugging​

  1. HTML Validation Tools
  2. Browser Developer Tools
  3. Accessibility Testing
  4. Performance Profiling
  5. Cross-Browser Compatibility
  6. Mobile-First Development
  7. Responsive Design Principles

🌟 2025 Trending Topics​

  1. Container Queries
  2. CSS Grid & Flexbox Integration
  3. Web Assembly (WASM) Integration
  4. Micro-frontends & HTML
  5. Edge-Side Includes (ESI)
  6. Streaming HTML
  7. HTML Over The Wire (Hotwire)
  8. Declarative Shadow DOM

📚 Essential Resources​