JavaScript is a programming language that is primarily used to create interactive and dynamic websites. It is a client-side scripting language, which means that the code is executed on the user’s computer rather than on the server. JavaScript can be used to create things like drop-down menus, pop-ups, and interactive forms. It can also be used to create complex web applications and can be used in conjunction with other technologies such as HTML and CSS.

(Ed: written by ChatGPT; verified by jrivett.)