Variables.

Second class. A budget has numbers you reuse — for example monthly income. Instead of writing 1500 everywhere, store it in a variable.

Modern JavaScript uses const (do not reassign) or let (may change later). Syntax: const income = 1500;

The name is a label. The value is the content. console.log(income) prints the number, not the word income.

Mini example:

const tip = 10; console.log(tip);

Common mistake: income = 1500 without const/let (fails in strict mode); or "1500" in quotes when you need a number.