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HTML · LESSON 70

HTML Coding Standards and Validation

By Ratan Updated: 16 Oct 2026

Validate HTML documents using the official W3C Markup Validation Service.

Level: Beginner to Advanced
Duration: ~60 Mins Deep-Dive

1. HTML Coding Standards & Validation

Adhering to international web coding standards ensures your websites load consistently across different platforms, devices, and browser engines.

2. Validating Code with the W3C Markup Validator

The World Wide Web Consortium (W3C) provides an official online validation tool at validator.w3.org. Running your HTML through this validator checks for:

  • Deprecated tags (e.g.
    , , ).
  • Duplicate element id attributes.
  • Missing mandatory attributes (e.g. missing alt on ).
  • Improperly nested tags (e.g. placing a block-level
    inside an inline ).
  • 3. Automated Linting with HTMLHint & Prettier

    Modern development teams automate compliance using tools like htmlhint and prettier inside VS Code, catching formatting defects on every file save.

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