JavaScript is a programming language used to add interactivity and dynamic behavior to web pages. It is often described as the 'interaction layer' of web development, enabling features like user input handling, animations, and real-time updates. While not a framework itself, JavaScript is foundational to frontend development and is used in conjunction with HTML and CSS. It is widely adopted by developers for building interactive user interfaces and is supported by major platforms including browsers and tools like Supabase and SitePoint. JavaScript is used by developers across the web to create dynamic experiences, from simple toggles to complex data visualizations.