We call it a statistic. Now, you might be saying, well, what notation do we use if somehow we are able to measure it for the population? Well, let's say we can't even measure it for the population, but we at least wanna denote what the population mean is. Well, if you wanna do that, the population mean is usually denoted by the Greek letter mu. So the population mean is usually denoted by the Greek letter mu. And so in a lot of statistics, it's calculating a sample mean in an attempt to estimate this thing that you might not know, the population mean. And these calculations on the entire population, sometimes you might be able to do it, oftentimes you will not be able to do it, these are called parameters.