Summary  
This chapter covers declaring and initializing constants with the `const` keyword, enforcing their immutability so values cannot be reassigned, which improves code clarity and prevents accidental mistakes.

General domain of usage  
Mathematical calculations

**Constants** are similar to variables however their value, as expressed by the name, is always **constant** or **unchanged**.

Definition

We can declare a constant using the `const` keyword, and it's important to initialize it at the same point as well. Following is the syntax for constant declaration & initialization:
```js
const constantName = data;
```

For example:
```js
const exampleConstant = 123;
```

Changing the value of a constant results in an error:
```js
const exampleConstant = 123;
exampleConstant = 1234; // Error here
```

The names of the constants follow the same naming rules as the variables.


Which keyword is used to declare a constant in JavaScript?

What happens if you try to reassign a value to a constant?

Which of the following correctly declares and initializes a constant in a single **statement**?

Dive into the world of the most popular language for front-end development – JavaScript. JavaScript is a language built into almost every browser and can be used for a wide variety of tasks. Learn the basic functionality and prepare yourself for the challenges and more advanced programming techniques.

An introduction to JavaScript, covering the basic syntax of the language along with key terms and concepts that form the foundation for learning advanced features. The section includes hands-on tasks designed to help practice these concepts and make the content easy to remember without effort.

Constants

1. What is a constant in JavaScript?

2. Which keyword is used to declare a constant in JavaScript?

3. What happens if you try to reassign a value to a constant?

4. Which of the following correctly declares and initializes a constant in a single statement?