HTML (HyperText Markup Language) is the standard markup language used to create the structure and layout of web pages. It serves as the backbone of the internet, defining elements such as headings, paragraphs, links, images, and other multimedia content. Web browsers read HTML documents and render them into the visual web pages that users interact with daily. HTML determines the semantic structure of a page, ensuring that content is organized logically for both users and search engines. HTML files are essential for web development and compliance testing. Developers use sample HTML files to test browser rendering compatibility, validate parsing logic in web scrapers, and ensure that accessibility standards (WCAG) are met. These files are also crucial for testing content management systems (CMS) and verifying that HTML sanitization libraries correctly filter out malicious code while preserving safe markup.