Summary  
This chapter covers how to declare constants using the `const` keyword—requiring initialization at declaration time and prohibiting any later reassignment to ensure values remain fixed and avoid accidental changes.  

General domain of usage  
Mathematical computations (e.g., using a constant like π in 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**?

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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?

Awesome!

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?