A *global object* is the object that provides access to built-in functions and values, defined by the specification and the environment.

In a browser it is named "window", for Node.JS it is "global", for other environments it may have another name.

So we can call `alert` two ways:

```js run

alert("Hello");

window.alert("Hello");

Also we can access `Math` as `window.Math`:

```js run

alert( window.Math.min(5,1,4) ); // 1

Normally no one does so. Using the global object is generally not a good thing, it's recommended to evade that.

**The global object is not a global Lexical Environment.**

For historical reasons it also gives access to global Function Declarations and `var` variables, but not `let/const` variables:

```js

var phrase = "Hello";

let user = "John";

function sayHi() {

alert(phrase + ', ' + user);

}

alert( window.phrase ); // Hello

alert( window.sayHi ); // function

alert( window.user ); // undefined

In the example above you can clearly see that `let user` is not in `window`.

That's because the idea of a global object as a way to access "all global things" comes from ancient times. In modern scripts its use is not recommended, and modern language features like `let/const` do not make friends with it.

TODO

As said ed in the [specification](https://tc39.github.io/ecma262/#sec-lexical-environments), the global object provides access to *some* global variables.