JavaScript is a high-level programming language that is primarily used to add interactivity and dynamic functionality to websites. It is one of the core technologies of web development, along with HTML (Hypertext Markup Language) and CSS (Cascading Style Sheets).

JavaScript allows developers to create interactive elements, manipulate web page content, respond to user actions, and dynamically update the appearance and behavior of web pages without requiring a page reload. It runs on the client side, meaning it is executed by the user’s web browser.