Programming

variable

A variable is a named box that holds a value. You give the box a label — like score or username — put something inside it, and later you can read what's there or swap it for something new. It's the most basic building block of almost every program.

The name is the whole point: instead of repeating a value all over your code, you store it once and refer to it by name. Change what's in the box in one place, and everywhere that reads it sees the new value.

Why 'variable'? Because the contents can vary — they change over time. score might start at 0, climb to 10, then reset. The label stays the same; what's inside is free to move.

let score = 0
score = score + 10
console.log(score)  // 10

The label 'score' stays put; the value inside changes from 0 to 10.

A constant is a variable you promise never to change after setting it — same box, lid glued shut.

Also called

varbindingidentifier