window is an object that exists in the global scope of an application. In JavaScript there is always an object in a global scope where all methods and properties are hung. This object varies according to the environment where the application is being executed - in Node.JS (a platform for JavaScript to be run on the back-end) it is the global object. In the front-end, this object is called window (the browser window) and a lot of methods and properties are stored in this object. When using its properties, we do not need to use the word window, since the browser can infer that it is a property that belongs to window. For example: console.log exists in the window object.