What is a variable in JavaScript

You can declare a variable using the `var`, `let`, or `const` keyword.

Here's an example:

var age = 21;
let name = "Tom";
const PI = 3.14;

In the example above, age, name, and PI are variables. age holds the value 21, name holds the value "Tom", and PI holds the value 3.14. You can change the value of a variable declared with var or let later in the code, but a variable declared with const cannot be reassigned a new value.