Variables

A variable is a named place to store a value so you can use or change it later.

Real-world analogy: a variable is like a labeled box — write a label on it, put something inside, and read or replace the contents later by referring to the label.

Syntax

let name = "Ada";
const age = 25;

Example

let score = 10;
console.log(score);
score = 20;
console.log(score);

Expected output

10
20

Use let for a variable you'll reassign, and const for one you won't — prefer const by default, and switch to let only when you actually need to change the value. Avoid the older var keyword; it has confusing scoping rules that let/const fix.

Common mistakes

• Trying to reassign a const variable — TypeError: Assignment to constant variable.
• Using a variable before declaring it.

Practice

Create a variable called city holding your city's name, then log it.

const city = "Lagos";
console.log(city);