ELI5: Explain Like I'm 5

Real number

Real numbers are numbers that you can use to count, measure, or describe something. You can think of them like regular numbers, but they also include decimal numbers (like 3.14) and negative numbers (like -1). Real numbers are "real" because they can be used to describe real-world things like the temperature outside, the weight of something, or the number of days in a month. They all help us measure and understand the world around us.