JavaScript is a programming language used (mostly) for Web Development. It's the programming language responsible for a large lot of the interactions you perform when you're clicking around (submitting forms, dragging and dropping etc) on a Webpage.
All modern browsers can interpret JavaScript and all you need to get started is a text editor (e.g TextEdit, Notepad), but you're advised to get a slightly fancier kind of text editor called an IDE (Integrated Development Environment) like SublimeText, Atom or VS Code.
In this chapter, you'll be getting an introduction to writing the latest version of JavaScript.