Variable in JavaScript

What is a Variable?

A variable is a named container used to store data values that can be used and modified throughout a program.

Declaring Variables

var name = "John";
let age = 25;
const PI = 3.14;

Naming Rules

• Must begin with a letter, underscore _, or dollar sign $.
• Cannot start with a digit or contain spaces.
• Case-sensitive — age and Age are different variables.
• Cannot use reserved keywords as variable names.