HTML (HyperText Markup Language) is the standard markup language for creating web pages and web applications. It provides the structure of a web page by defining elements such as headings, paragraphs, links, images, and forms using tags and attributes. HTML works in conjunction with CSS and JavaScript to build visually appealing and interactive web pages. It is the foundational technology of the web, enabling browsers to display content correctly and ensuring that web pages are accessible and usable across different devices and platforms.