What Is a Vector?

Temperature is 22°. That's all you need — a single number. But the wind is 15 km/h blowing northeast. Strip the direction and you've lost the whole story: a 15 km/h wind north pushes a drone somewhere very different than a 15 km/h wind south. Quantities like temperature are scalars — just a size. Quantities like wind are vectors — a size AND a direction, drawn as an arrow.