Summary  
This chapter explains JavaScript’s primitive data types—strings, numbers, booleans, null, and undefined—and how to declare and use them.

General domain of usage  
Data management in applications

JavaScript works with different types of data. The most common ones are strings, numbers, and booleans.

A string is text:

```javascript 
const name = "John";
```

A number is a numeric value:

```javascript 
const age = 25;
```

A boolean represents a true or false value:

```javascript 
const isLoggedIn = true;
```

There are also two special values: `null` and `undefined`.

`undefined` means a variable has been declared but has no value:

```javascript 
let value;
console.log(value); // undefined
```

`null` is an intentional absence of value:

```javascript 
const data = null;
```

Understanding these types is important because JavaScript behaves differently depending on the type of data you are working with.


Learn the core concepts of JavaScript needed for backend development, including variables, data structures, functions, and asynchronous code. Practice working with real data and understand how JavaScript behaves outside the browser. Build a strong foundation before moving on to Node.js and server-side development.

Data Types in JavaScript