HTML5
HTML5 is the fifth and current major version of the HyperText Markup Language, the standard markup language used to structure and present content on the World Wide Web. It introduces new semantic elements, multimedia support (audio and video), canvas for graphics, and APIs for enhanced interactivity, while maintaining backward compatibility with earlier HTML versions.
Developers should learn HTML5 as it is the foundational language for all web development, essential for creating modern, responsive, and accessible websites and web applications. It is used in virtually every web project, from simple static pages to complex single-page applications, and its features like local storage and geolocation enable richer user experiences without plugins.