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# JavaScript Variables

JavaScript variable is a container that can hold a value, such as a number or a string. Variables are declared using the `var`, `let`, or `const` keywords.

Here's an example of declaring a variable using the `var` keyword:

```javascript
javascript var x = 2;
```

This declares a variable named `x` and assigns it the value of `2`.

The `let` and `const` keywords provide additional features for managing variables.

With `let`, you can declare a variable that is block-scoped, which means it only exists within the block of code where it was declared. For example,

```javascript
javascript let y = 100;
if (true) {
  let y = 20;
  console.log(y); // output: 20
}
console.log(y); // output: 10
```

In this example, you declared a variable named `y` and assigned it the value of `100`. Within the `if` statement block, we declare another variable also named `y` and assign it the value of `20`. This new `y` variable only exists within the `if` block, so when we log its value, it outputs `20`. When we log the value of `y` again outside of the `if` block, it outputs `100`, which is the value of the original `y` variable.

The `const` keyword declares a variable that is also block-scoped, but it cannot be reassigned once it has been declared unlike the `Let` variable. For example,

```javascript
javascriptCopy codeconst z = 15;
z = 20; // This will throw an error
```

In this example, you will declare a variable named `z` and assign it the value of `15`. When you try to reassign it to `20`, you will get an error because `z` is a `const` variable and cannot be reassigned.