Definition
Variance measures how spread out a set of numbers is from their average value. It's a statistical term that quantifies the dispersion or variability within a dataset. Think of it as how much the grades in your class differ from the average grade or how consistently a basketball player scores points each game. A high variance means the numbers are widely scattered, while a low variance means they're clustered closely together. Variance is used to assess risk and make informed decisions based on data.