The distribution of a sample statistic (mean, median, etc.) from an infinite number of samples is called a "sampling distribution". In this simulation, the sampling distribution is approximated by including a sufficiently large number of samples in the distribution. Each sample, on the other hand, consists of a fixed number of data points from the population (called "sample size"), and in turn, contributes only one data point to the sampling distribution. The standard deviation of a sampling distribution is called the "standard error", as opposed to the standard deviation in the population.